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commit 1b99973f1c82707e46e8cb9416865a1e955e8f8c upstream.
In submit_bio, we count vm events by check READ/WRITE.
But actually DISCARD_NOBARRIER also has the WRITE flag set.
It looks as if in blkdev_issue_discard, we also add a
page as the payload and the bio_has_data check isn't enough.
So add another check for discard bio.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit c10b61f0910466b4b99c266a7d76ac4390743fb5 upstream.
Hi,
A user reported a kernel bug when running a particular program that did
the following:
created 32 threads
- each thread took a mutex, grabbed a global offset, added a buffer size
to that offset, released the lock
- read from the given offset in the file
- created a new thread to do the same
- exited
The result is that cfq's close cooperator logic would trigger, as the
threads were issuing I/O within the mean seek distance of one another.
This workload managed to routinely trigger a use after free bug when
walking the list of merge candidates for a particular cfqq
(cfqq->new_cfqq). The logic used for merging queues looks like this:
static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
{
int process_refs, new_process_refs;
struct cfq_queue *__cfqq;
/* Avoid a circular list and skip interim queue merges */
while ((__cfqq = new_cfqq->new_cfqq)) {
if (__cfqq == cfqq)
return;
new_cfqq = __cfqq;
}
process_refs = cfqq_process_refs(cfqq);
/*
* If the process for the cfqq has gone away, there is no
* sense in merging the queues.
*/
if (process_refs == 0)
return;
/*
* Merge in the direction of the lesser amount of work.
*/
new_process_refs = cfqq_process_refs(new_cfqq);
if (new_process_refs >= process_refs) {
cfqq->new_cfqq = new_cfqq;
atomic_add(process_refs, &new_cfqq->ref);
} else {
new_cfqq->new_cfqq = cfqq;
atomic_add(new_process_refs, &cfqq->ref);
}
}
When a merge candidate is found, we add the process references for the
queue with less references to the queue with more. The actual merging
of queues happens when a new request is issued for a given cfqq. In the
case of the test program, it only does a single pread call to read in
1MB, so the actual merge never happens.
Normally, this is fine, as when the queue exits, we simply drop the
references we took on the other cfqqs in the merge chain:
/*
* If this queue was scheduled to merge with another queue, be
* sure to drop the reference taken on that queue (and others in
* the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
*/
__cfqq = cfqq->new_cfqq;
while (__cfqq) {
if (__cfqq == cfqq) {
WARN(1, "cfqq->new_cfqq loop detected\n");
break;
}
next = __cfqq->new_cfqq;
cfq_put_queue(__cfqq);
__cfqq = next;
}
However, there is a hole in this logic. Consider the following (and
keep in mind that each I/O keeps a reference to the cfqq):
q1->new_cfqq = q2 // q2 now has 2 process references
q3->new_cfqq = q2 // q2 now has 3 process references
// the process associated with q2 exits
// q2 now has 2 process references
// queue 1 exits, drops its reference on q2
// q2 now has 1 process reference
// q3 exits, so has 0 process references, and hence drops its references
// to q2, which leaves q2 also with 0 process references
q4 comes along and wants to merge with q3
q3->new_cfqq still points at q2! We follow that link and end up at an
already freed cfqq.
So, the fix is to not follow a merge chain if the top-most queue does
not have a process reference, otherwise any queue in the chain could be
already freed. I also changed the logic to disallow merging with a
queue that does not have any process references. Previously, we did
this check for one of the merge candidates, but not the other. That
doesn't really make sense.
Without the attached patch, my system would BUG within a couple of
seconds of running the reproducer program. With the patch applied, my
system ran the program for over an hour without issues.
This addresses the following bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=16217
Thanks a ton to Phil Carns for providing the bug report and an excellent
reproducer.
[ Note for stable: this applies to 2.6.32/33/34 ].
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Reported-by: Phil Carns <carns@mcs.anl.gov>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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commit d02a2c077fb81f3224c770be62a318165b23b486 upstream.
I got below oops when unloading cfq-iosched. Considering scenario:
queue A merge to B, C merge to D and B will be merged to D. Before B is merged
to D, we do split B. We should put B's reference for D.
[ 807.768536] =============================================================================
[ 807.768539] BUG cfq_queue: Objects remaining on kmem_cache_close()
[ 807.768541] -----------------------------------------------------------------------------
[ 807.768543]
[ 807.768546] INFO: Slab 0xffffea0003e6b4e0 objects=26 used=1 fp=0xffff88011d584fd8 flags=0x200000000004082
[ 807.768550] Pid: 5946, comm: rmmod Tainted: G W 2.6.34-07097-gf4b87de-dirty #724
[ 807.768552] Call Trace:
[ 807.768560] [<ffffffff81104e8d>] slab_err+0x8f/0x9d
[ 807.768564] [<ffffffff811059e1>] ? flush_cpu_slab+0x0/0x93
[ 807.768569] [<ffffffff8164be52>] ? add_preempt_count+0xe/0xca
[ 807.768572] [<ffffffff8164bd9c>] ? sub_preempt_count+0xe/0xb6
[ 807.768577] [<ffffffff81648871>] ? _raw_spin_unlock+0x15/0x30
[ 807.768580] [<ffffffff8164bd9c>] ? sub_preempt_count+0xe/0xb6
[ 807.768584] [<ffffffff811061bc>] list_slab_objects+0x9b/0x19f
[ 807.768588] [<ffffffff8164bf0a>] ? add_preempt_count+0xc6/0xca
[ 807.768591] [<ffffffff81109e27>] kmem_cache_destroy+0x13f/0x21d
[ 807.768597] [<ffffffffa000ff13>] cfq_slab_kill+0x1a/0x43 [cfq_iosched]
[ 807.768601] [<ffffffffa000ffcf>] cfq_exit+0x93/0x9e [cfq_iosched]
[ 807.768606] [<ffffffff810973a2>] sys_delete_module+0x1b1/0x219
[ 807.768612] [<ffffffff8102fb5b>] system_call_fastpath+0x16/0x1b
[ 807.768618] INFO: Object 0xffff88011d584618 @offset=1560
[ 807.768622] INFO: Allocated in cfq_get_queue+0x11e/0x274 [cfq_iosched] age=7173 cpu=1 pid=5496
[ 807.768626] =============================================================================
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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with CONFIG_PROVE_RCU=y, a warning can be triggered:
# mount -t cgroup -o blkio xxx /mnt
# mkdir /mnt/subgroup
...
kernel/cgroup.c:4442 invoked rcu_dereference_check() without protection!
...
To fix this, we avoid caling css_depth() here, which is a bit simpler
than the original code.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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It is necessary to be in an RCU read-side critical section when invoking
css_id(), so this patch adds one to blkiocg_add_blkio_group(). This is
actually a false positive, because this is called at initialization time
and hence always refers to the root cgroup, which cannot go away.
[ 103.790505] ===================================================
[ 103.790509] [ INFO: suspicious rcu_dereference_check() usage. ]
[ 103.790511] ---------------------------------------------------
[ 103.790514] kernel/cgroup.c:4432 invoked rcu_dereference_check() without protection!
[ 103.790517]
[ 103.790517] other info that might help us debug this:
[ 103.790519]
[ 103.790521]
[ 103.790521] rcu_scheduler_active = 1, debug_locks = 1
[ 103.790524] 4 locks held by bash/4422:
[ 103.790526] #0: (&buffer->mutex){+.+.+.}, at: [<ffffffff8114befa>] sysfs_write_file+0x3c/0x144
[ 103.790537] #1: (s_active#102){.+.+.+}, at: [<ffffffff8114bfa5>] sysfs_write_file+0xe7/0x144
[ 103.790544] #2: (&q->sysfs_lock){+.+.+.}, at: [<ffffffff812263b1>] queue_attr_store+0x49/0x8f
[ 103.790552] #3: (&(&blkcg->lock)->rlock){......}, at: [<ffffffff8122e4db>] blkiocg_add_blkio_group+0x2b/0xad
[ 103.790560]
[ 103.790561] stack backtrace:
[ 103.790564] Pid: 4422, comm: bash Not tainted 2.6.34-rc4-blkio-second-crash #81
[ 103.790567] Call Trace:
[ 103.790572] [<ffffffff81068f57>] lockdep_rcu_dereference+0x9d/0xa5
[ 103.790577] [<ffffffff8107fac1>] css_id+0x44/0x57
[ 103.790581] [<ffffffff8122e503>] blkiocg_add_blkio_group+0x53/0xad
[ 103.790586] [<ffffffff81231936>] cfq_init_queue+0x139/0x32c
[ 103.790591] [<ffffffff8121f2d0>] elv_iosched_store+0xbf/0x1bf
[ 103.790595] [<ffffffff812263d8>] queue_attr_store+0x70/0x8f
[ 103.790599] [<ffffffff8114bfa5>] ? sysfs_write_file+0xe7/0x144
[ 103.790603] [<ffffffff8114bfc6>] sysfs_write_file+0x108/0x144
[ 103.790609] [<ffffffff810f527f>] vfs_write+0xae/0x10b
[ 103.790612] [<ffffffff81069863>] ? trace_hardirqs_on_caller+0x10c/0x130
[ 103.790616] [<ffffffff810f539c>] sys_write+0x4a/0x6e
[ 103.790622] [<ffffffff81002b5b>] system_call_fastpath+0x16/0x1b
[ 103.790625]
Located-by: Miles Lane <miles.lane@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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blk_rq_timed_out_timer() relied on blk_add_timer() never returning a
timer value of zero, but commit 7838c15b8dd18e78a523513749e5b54bda07b0cb
removed the code that bumped this value when it was zero.
Therefore when jiffies is near wrap we could get unlucky & not set the
timeout value correctly.
This patch uses a flag to indicate that the timeout value was set and so
handles jiffies wrap correctly, and it keeps all the logic in one
function so should be easier to maintain in the future.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block: (34 commits)
cfq-iosched: Fix the incorrect timeslice accounting with forced_dispatch
loop: Update mtime when writing using aops
block: expose the statistics in blkio.time and blkio.sectors for the root cgroup
backing-dev: Handle class_create() failure
Block: Fix block/elevator.c elevator_get() off-by-one error
drbd: lc_element_by_index() never returns NULL
cciss: unlock on error path
cfq-iosched: Do not merge queues of BE and IDLE classes
cfq-iosched: Add additional blktrace log messages in CFQ for easier debugging
i2o: Remove the dangerous kobj_to_i2o_device macro
block: remove 16 bytes of padding from struct request on 64bits
cfq-iosched: fix a kbuild regression
block: make CONFIG_BLK_CGROUP visible
Remove GENHD_FL_DRIVERFS
block: Export max number of segments and max segment size in sysfs
block: Finalize conversion of block limits functions
block: Fix overrun in lcm() and move it to lib
vfs: improve writeback_inodes_wb()
paride: fix off-by-one test
drbd: fix al-to-on-disk-bitmap for 4k logical_block_size
...
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When CFQ dispatches requests forcefully due to a barrier or changing iosched,
it runs through all cfqq's dispatching requests and then expires each queue.
However, it does not activate a cfqq before flushing its IOs resulting in
using stale values for computing slice_used.
This patch fixes it by calling activate queue before flushing reuqests from
each queue.
This is useful mostly for barrier requests because when the iosched is changing
it really doesnt matter if we have incorrect accounting since we're going to
break down all structures anyway.
We also now expire the current timeslice before moving on with the dispatch
to accurately account slice used for that cfqq.
Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Currently, the io statistics for the root cgroup are maintained, but
they are not shown because the device information is not available at
the point that the root blkio cgroup is created. This patch updates
the device information when the statistics are updated so that the
statistics become visible.
Signed-off-by: Ricky Benitez <rickyb@google.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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elevator_get() not check the name length, if the name length > sizeof(elv),
elv will miss the '\0'. And elv buffer will be replace "-iosched" as something
like aaaaaaaaa, then call request_module() can load an not trust module.
Signed-off-by: Zhitong Wang <zhitong.wangzt@alibaba-inc.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
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Even if they are found to be co-operating.
The prio_trees do not have any IDLE cfqqs on them. cfq_close_cooperator()
is called from cfq_select_queue() and cfq_completed_request(). The latter
ensures that the close cooperator code does not get invoked if the current
cfqq is of class IDLE but the former doesn't seem to have any such checks.
So an IDLE cfqq may get merged with a BE cfqq from the same group which
should be avoided.
Signed-off-by: Divyesh Shah<dpshah@google.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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These have helped us debug some issues we've noticed in earlier IO
controller versions and should be useful now as well. The extra logging
covers:
- idling behavior. Since there are so many conditions based on which we decide
to idle or not, this patch adds a log message for some conditions that we've
found useful.
- workload slices and current prio and workload type
Changelog from v1:
o moved log message from cfq_set_active_queue() to __cfq_set_active_queue()
o changed queue_count to st->count
Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Conflicts:
block/Kconfig
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Alex Shi reported a kbuild regression which is about 10% performance lost.
He bisected to this commit: 3dde36ddea3e07dd025c4c1ba47edec91606fec0.
The reason is cfqq_close() can't find close cooperator. Restoring
cfq_rq_close()'s threshold to original value makes the regression go away.
Since for_preempt parameter isn't used anymore, this patch deletes it.
Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Make the config visible, so we can choose from CONFIG_BLK_CGROUP=y
and CONFIG_BLK_CGROUP=m when CONFIG_IOSCHED_CFQ=m.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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These two values are useful when debugging issues surrounding maximum
I/O size. Put them in sysfs with the rest of the queue limits.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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lcm() was defined to take integer-sized arguments. The supplied
arguments are multiplied, however, causing us to overflow given
sufficiently large input. That in turn led to incorrect optimal I/O
size reporting in some cases (RAID over RAID).
Switch lcm() over to unsigned long similar to gcd() and move the
function from blk-settings.c to lib.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (56 commits)
doc: fix typo in comment explaining rb_tree usage
Remove fs/ntfs/ChangeLog
doc: fix console doc typo
doc: cpuset: Update the cpuset flag file
Fix of spelling in arch/sparc/kernel/leon_kernel.c no longer needed
Remove drivers/parport/ChangeLog
Remove drivers/char/ChangeLog
doc: typo - Table 1-2 should refer to "status", not "statm"
tree-wide: fix typos "ass?o[sc]iac?te" -> "associate" in comments
No need to patch AMD-provided drivers/gpu/drm/radeon/atombios.h
devres/irq: Fix devm_irq_match comment
Remove reference to kthread_create_on_cpu
tree-wide: Assorted spelling fixes
tree-wide: fix 'lenght' typo in comments and code
drm/kms: fix spelling in error message
doc: capitalization and other minor fixes in pnp doc
devres: typo fix s/dev/devm/
Remove redundant trailing semicolons from macros
fix typo "definetly" -> "definitely" in comment
tree-wide: s/widht/width/g typo in comments
...
Fix trivial conflict in Documentation/laptops/00-INDEX
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Modify the Block I/O cgroup subsystem to be able to be built as a module.
As the CFQ disk scheduler optionally depends on blk-cgroup, config options
in block/Kconfig, block/Kconfig.iosched, and block/blk-cgroup.h are
enhanced to support the new module dependency.
Signed-off-by: Ben Blum <bblum@andrew.cmu.edu>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Conflicts:
Documentation/filesystems/proc.txt
arch/arm/mach-u300/include/mach/debug-macro.S
drivers/net/qlge/qlge_ethtool.c
drivers/net/qlge/qlge_main.c
drivers/net/typhoon.c
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Constify struct sysfs_ops.
This is part of the ops structure constification
effort started by Arjan van de Ven et al.
Benefits of this constification:
* prevents modification of data that is shared
(referenced) by many other structure instances
at runtime
* detects/prevents accidental (but not intentional)
modification attempts on archs that enforce
read-only kernel data at runtime
* potentially better optimized code as the compiler
can assume that the const data cannot be changed
* the compiler/linker move const data into .rodata
and therefore exclude them from false sharing
Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: David Teigland <teigland@redhat.com>
Acked-by: Matt Domsch <Matt_Domsch@dell.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: Hans J. Koch <hjk@linutronix.de>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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As the comment says the initial value of last_waited is never used, so
there is no need to initialise it with the current jiffies. Jiffies is
hot enough without accessing it for no reason.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Reorder cfq_rb_root to remove 8 bytes of padding on 64 bit builds.
Consequently removing 56 bytes from cfq_group and 64 bytes from
cfq_data.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Currently a queue can only dispatch up to 4 requests if there are other queues.
This isn't optimal, device can handle more requests, for example, AHCI can
handle 31 requests. I can understand the limit is for fairness, but we could
do a tweak: if the queue still has a lot of slice left, sounds we could
ignore the limit. Test shows this boost my workload (two thread randread of
a SSD) from 78m/s to 100m/s.
Thanks for suggestions from Corrado and Vivek for the patch.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Counters for requests "in flight" and "in driver" are used asymmetrically
in cfq_may_dispatch, and have slightly different meaning.
We split the rq_in_flight counter (was sync_flight) to count both sync
and async requests, in order to use this one, which is more accurate in
some corner cases.
The rq_in_driver counter is coalesced, since individual sync/async counts
are not used any more.
Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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CFQ currently applies the same logic of detecting seeky queues and
grouping them together for rotational disks as well as SSDs.
For SSDs, the time to complete a request doesn't depend on the
request location, but only on the size.
This patch therefore changes the criterion to group queues by
request size in case of SSDs, in order to achieve better fairness.
Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Current seeky detection is based on average seek lenght.
This is suboptimal, since the average will not distinguish between:
* a process doing medium sized seeks
* a process doing some sequential requests interleaved with larger seeks
and even a medium seek can take lot of time, if the requested sector
happens to be behind the disk head in the rotation (50% probability).
Therefore, we change the seeky queue detection to work as follows:
* each request can be classified as sequential if it is very close to
the current head position, i.e. it is likely in the disk cache (disks
usually read more data than requested, and put it in cache for
subsequent reads). Otherwise, the request is classified as seeky.
* an history window of the last 32 requests is kept, storing the
classification result.
* A queue is marked as seeky if more than 1/8 of the last 32 requests
were seeky.
This patch fixes a regression reported by Yanmin, on mmap 64k random
reads.
Reported-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Except for SCSI no device drivers distinguish between physical and
hardware segment limits. Consolidate the two into a single segment
limit.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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The block layer calling convention is blk_queue_<limit name>.
blk_queue_max_sectors predates this practice, leading to some confusion.
Rename the function to appropriately reflect that its intended use is to
set max_hw_sectors.
Also introduce a temporary wrapper for backwards compability. This can
be removed after the merge window is closed.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Add a BLK_ prefix to block layer constants.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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blk_queue_max_hw_sectors is no longer called by any subsystem and can be
removed.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
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Clarify blk_queue_max_sectors and update documentation.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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There's no need to take css reference here, for the caller
has already called rcu_read_lock() to prevent cgroup from
being removed.
Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Conflicts:
include/linux/blkdev.h
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Now that the bio list management stuff is generic, convert
generic_make_request to use bio lists instead of its own private bio
list implementation.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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This reverts commit fb1e75389bd06fd5987e9cda1b4e0305c782f854.
"Benjamin S." <sbenni@gmx.de> reports that the patch in question
causes a big drop in sequential throughput for him, dropping from
200MB/sec down to only 70MB/sec.
Needs to be investigated more fully, for now lets just revert the
offending commit.
Conflicts:
include/linux/blkdev.h
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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This removes 8 bytes of padding from struct cfq_queue on 64 bit builds,
shrinking it's size to 256 bytes, so fitting into 1 fewer cachelines and
allowing 1 more object/slab in it's kmem_cache.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
----
patch against 2.6.33-rc8
tested on x86_64 AMDX2
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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In particular, several occurances of funny versions of 'success',
'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address',
'beginning', 'desirable', 'separate' and 'necessary' are fixed.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Joe Perches <joe@perches.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Currently we split seeky coop queues after 1s, which is too big. Below patch
marks seeky coop queue split_coop flag after one slice. After that, if new
requests come in, the queues will be splitted. Patch is suggested by Corrado.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Corrado Zoccolo <czoccolo@gmail.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Few weeks back, Shaohua Li had posted similar patch. I am reposting it
with more test results.
This patch does two things.
- Do not idle on async queues.
- It also changes the write queue depth CFQ drives (cfq_may_dispatch()).
Currently, we seem to driving queue depth of 1 always for WRITES. This is
true even if there is only one write queue in the system and all the logic
of infinite queue depth in case of single busy queue as well as slowly
increasing queue depth based on last delayed sync request does not seem to
be kicking in at all.
This patch will allow deeper WRITE queue depths (subjected to the other
WRITE queue depth contstraints like cfq_quantum and last delayed sync
request).
Shaohua Li had reported getting more out of his SSD. For me, I have got
one Lun exported from an HP EVA and when pure buffered writes are on, I
can get more out of the system. Following are test results of pure
buffered writes (with end_fsync=1) with vanilla and patched kernel. These
results are average of 3 sets of run with increasing number of threads.
AVERAGE[bufwfs][vanilla]
-------
job Set NR ReadBW(KB/s) MaxClat(us) WriteBW(KB/s) MaxClat(us)
--- --- -- ------------ ----------- ------------- -----------
bufwfs 3 1 0 0 95349 474141
bufwfs 3 2 0 0 100282 806926
bufwfs 3 4 0 0 109989 2.7301e+06
bufwfs 3 8 0 0 116642 3762231
bufwfs 3 16 0 0 118230 6902970
AVERAGE[bufwfs] [patched kernel]
-------
bufwfs 3 1 0 0 270722 404352
bufwfs 3 2 0 0 206770 1.06552e+06
bufwfs 3 4 0 0 195277 1.62283e+06
bufwfs 3 8 0 0 260960 2.62979e+06
bufwfs 3 16 0 0 299260 1.70731e+06
I also ran buffered writes along with some sequential reads and some
buffered reads going on in the system on a SATA disk because the potential
risk could be that we should not be driving queue depth higher in presence
of sync IO going to keep the max clat low.
With some random and sequential reads going on in the system on one SATA
disk I did not see any significant increase in max clat. So it looks like
other WRITE queue depth control logic is doing its job. Here are the
results.
AVERAGE[brr, bsr, bufw together] [vanilla]
-------
job Set NR ReadBW(KB/s) MaxClat(us) WriteBW(KB/s) MaxClat(us)
--- --- -- ------------ ----------- ------------- -----------
brr 3 1 850 546345 0 0
bsr 3 1 14650 729543 0 0
bufw 3 1 0 0 23908 8274517
brr 3 2 981.333 579395 0 0
bsr 3 2 14149.7 1175689 0 0
bufw 3 2 0 0 21921 1.28108e+07
brr 3 4 898.333 1.75527e+06 0 0
bsr 3 4 12230.7 1.40072e+06 0 0
bufw 3 4 0 0 19722.3 2.4901e+07
brr 3 8 900 3160594 0 0
bsr 3 8 9282.33 1.91314e+06 0 0
bufw 3 8 0 0 18789.3 23890622
AVERAGE[brr, bsr, bufw mixed] [patched kernel]
-------
job Set NR ReadBW(KB/s) MaxClat(us) WriteBW(KB/s) MaxClat(us)
--- --- -- ------------ ----------- ------------- -----------
brr 3 1 837 417973 0 0
bsr 3 1 14357.7 591275 0 0
bufw 3 1 0 0 24869.7 8910662
brr 3 2 1038.33 543434 0 0
bsr 3 2 13351.3 1205858 0 0
bufw 3 2 0 0 18626.3 13280370
brr 3 4 913 1.86861e+06 0 0
bsr 3 4 12652.3 1430974 0 0
bufw 3 4 0 0 15343.3 2.81305e+07
brr 3 8 890 2.92695e+06 0 0
bsr 3 8 9635.33 1.90244e+06 0 0
bufw 3 8 0 0 17200.3 24424392
So looks like it might make sense to include this patch.
Thanks
Vivek
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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I triggered a lockdep warning as following.
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.33-rc2 #1
-------------------------------------------------------
test_io_control/7357 is trying to acquire lock:
(blkio_list_lock){+.+...}, at: [<c053a990>] blkiocg_weight_write+0x82/0x9e
but task is already holding lock:
(&(&blkcg->lock)->rlock){......}, at: [<c053a949>] blkiocg_weight_write+0x3b/0x9e
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&(&blkcg->lock)->rlock){......}:
[<c04583b7>] validate_chain+0x8bc/0xb9c
[<c0458dba>] __lock_acquire+0x723/0x789
[<c0458eb0>] lock_acquire+0x90/0xa7
[<c0692b0a>] _raw_spin_lock_irqsave+0x27/0x5a
[<c053a4e1>] blkiocg_add_blkio_group+0x1a/0x6d
[<c053cac7>] cfq_get_queue+0x225/0x3de
[<c053eec2>] cfq_set_request+0x217/0x42d
[<c052c8a6>] elv_set_request+0x17/0x26
[<c0532a0f>] get_request+0x203/0x2c5
[<c0532ae9>] get_request_wait+0x18/0x10e
[<c0533470>] __make_request+0x2ba/0x375
[<c0531985>] generic_make_request+0x28d/0x30f
[<c0532da7>] submit_bio+0x8a/0x8f
[<c04d827a>] submit_bh+0xf0/0x10f
[<c04d91d2>] ll_rw_block+0xc0/0xf9
[<f86e9705>] ext3_find_entry+0x319/0x544 [ext3]
[<f86eae58>] ext3_lookup+0x2c/0xb9 [ext3]
[<c04c3e1b>] do_lookup+0xd3/0x172
[<c04c56c8>] link_path_walk+0x5fb/0x95c
[<c04c5a65>] path_walk+0x3c/0x81
[<c04c5b63>] do_path_lookup+0x21/0x8a
[<c04c66cc>] do_filp_open+0xf0/0x978
[<c04c0c7e>] open_exec+0x1b/0xb7
[<c04c1436>] do_execve+0xbb/0x266
[<c04081a9>] sys_execve+0x24/0x4a
[<c04028a2>] ptregs_execve+0x12/0x18
-> #1 (&(&q->__queue_lock)->rlock){..-.-.}:
[<c04583b7>] validate_chain+0x8bc/0xb9c
[<c0458dba>] __lock_acquire+0x723/0x789
[<c0458eb0>] lock_acquire+0x90/0xa7
[<c0692b0a>] _raw_spin_lock_irqsave+0x27/0x5a
[<c053dd2a>] cfq_unlink_blkio_group+0x17/0x41
[<c053a6eb>] blkiocg_destroy+0x72/0xc7
[<c0467df0>] cgroup_diput+0x4a/0xb2
[<c04ca473>] dentry_iput+0x93/0xb7
[<c04ca4b3>] d_kill+0x1c/0x36
[<c04cb5c5>] dput+0xf5/0xfe
[<c04c6084>] do_rmdir+0x95/0xbe
[<c04c60ec>] sys_rmdir+0x10/0x12
[<c04027cc>] sysenter_do_call+0x12/0x32
-> #0 (blkio_list_lock){+.+...}:
[<c0458117>] validate_chain+0x61c/0xb9c
[<c0458dba>] __lock_acquire+0x723/0x789
[<c0458eb0>] lock_acquire+0x90/0xa7
[<c06929fd>] _raw_spin_lock+0x1e/0x4e
[<c053a990>] blkiocg_weight_write+0x82/0x9e
[<c0467f1e>] cgroup_file_write+0xc6/0x1c0
[<c04bd2f3>] vfs_write+0x8c/0x116
[<c04bd7c6>] sys_write+0x3b/0x60
[<c04027cc>] sysenter_do_call+0x12/0x32
other info that might help us debug this:
1 lock held by test_io_control/7357:
#0: (&(&blkcg->lock)->rlock){......}, at: [<c053a949>] blkiocg_weight_write+0x3b/0x9e
stack backtrace:
Pid: 7357, comm: test_io_control Not tainted 2.6.33-rc2 #1
Call Trace:
[<c045754f>] print_circular_bug+0x91/0x9d
[<c0458117>] validate_chain+0x61c/0xb9c
[<c0458dba>] __lock_acquire+0x723/0x789
[<c0458eb0>] lock_acquire+0x90/0xa7
[<c053a990>] ? blkiocg_weight_write+0x82/0x9e
[<c06929fd>] _raw_spin_lock+0x1e/0x4e
[<c053a990>] ? blkiocg_weight_write+0x82/0x9e
[<c053a990>] blkiocg_weight_write+0x82/0x9e
[<c0467f1e>] cgroup_file_write+0xc6/0x1c0
[<c0454df5>] ? trace_hardirqs_off+0xb/0xd
[<c044d93a>] ? cpu_clock+0x2e/0x44
[<c050e6ec>] ? security_file_permission+0xf/0x11
[<c04bcdda>] ? rw_verify_area+0x8a/0xad
[<c0467e58>] ? cgroup_file_write+0x0/0x1c0
[<c04bd2f3>] vfs_write+0x8c/0x116
[<c04bd7c6>] sys_write+0x3b/0x60
[<c04027cc>] sysenter_do_call+0x12/0x32
To prevent deadlock, we should take locks as following sequence:
blkio_list_lock -> queue_lock -> blkcg_lock.
The following patch should fix this bug.
Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
|
Updated 'nomerges' tunable to accept a value of '2' - indicating that _no_
merges at all are to be attempted (not even the simple one-hit cache).
The following table illustrates the additional benefit - 5 minute runs of
a random I/O load were applied to a dozen devices on a 16-way x86_64 system.
nomerges Throughput %System Improvement (tput / %sys)
-------- ------------ ----------- -------------------------
0 12.45 MB/sec 0.669365609
1 12.50 MB/sec 0.641519199 0.40% / 2.71%
2 12.52 MB/sec 0.639849750 0.56% / 2.96%
Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
|
In cfq_should_preempt(), we currently allow some cases where a non-RT request
can preempt an ongoing RT cfqq timeslice. This should not happen.
Examples include:
o A sync_noidle wl type non-RT request pre-empting a sync_noidle wl type cfqq
on which we are idling.
o Once we have per-cgroup async queues, a non-RT sync request pre-empting a RT
async cfqq.
Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
|
All callers of the stacking functions use 512-byte sector units rather
than byte offsets. Simplify the code so the stacking functions take
sectors when specifying data offsets.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
|
It isn't used anymore, since AS was deleted.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
|
DM does not want to know about partition offsets. Add a partition-aware
wrapper that DM can use when stacking block devices.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
|
Discard alignment reporting for partitions was incorrect. Update to
match the algorithm used elsewhere.
The alignment can be negative (misaligned). Fix format string
accordingly.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
|
The top device misalignment flag would not be set if the added bottom
device was already misaligned as opposed to causing a stacking failure.
Also massage the reporting so that an error is only returned if adding
the bottom device caused the misalignment. I.e. don't return an error
if the top is already flagged as misaligned.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
|
