summaryrefslogtreecommitdiff
path: root/Documentation/cpusets.txt
AgeCommit message (Collapse)Author
2007-04-02[PATCH] CPUSETS: add mems to basic usage documentationSimon Horman
It seems that there must be at least one node in mems and at least one CPU in cpus in order to be able to assign tasks to a cpuset. This makes sense. And I think it would also make sense to include a mems setting in the basic usage section of the documentation. I also wonder if something logged to dmsg, explaining why a write failed, would be a good enhancement. I ended up having rummage arround in cpuset.c in order to work out why my configuration was failing. Signed-off-by: Simon Horman <horms@verge.net.au> Acked-by: Paul Jackson <pj@sgi.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-09-29[PATCH] cpuset: top_cpuset tracks hotplug changes to node_online_mapPaul Jackson
Change the list of memory nodes allowed to tasks in the top (root) nodeset to dynamically track what cpus are online, using a call to a cpuset hook from the memory hotplug code. Make this top cpus file read-only. On systems that have cpusets configured in their kernel, but that aren't actively using cpusets (for some distros, this covers the majority of systems) all tasks end up in the top cpuset. If that system does support memory hotplug, then these tasks cannot make use of memory nodes that are added after system boot, because the memory nodes are not allowed in the top cpuset. This is a surprising regression over earlier kernels that didn't have cpusets enabled. One key motivation for this change is to remain consistent with the behaviour for the top_cpuset's 'cpus', which is also read-only, and which automatically tracks the cpu_online_map. This change also has the minor benefit that it fixes a long standing, little noticed, minor bug in cpusets. The cpuset performance tweak to short circuit the cpuset_zone_allowed() check on systems with just a single cpuset (see 'number_of_cpusets', in linux/cpuset.h) meant that simply changing the 'mems' of the top_cpuset had no affect, even though the change (the write system call) appeared to succeed. With the following change, that write to the 'mems' file fails -EACCES, and the 'mems' file stubbornly refuses to be changed via user space writes. Thus no one should be mislead into thinking they've changed the top_cpusets's 'mems' when in affect they haven't. In order to keep the behaviour of cpusets consistent between systems actively making use of them and systems not using them, this patch changes the behaviour of the 'mems' file in the top (root) cpuset, making it read only, and making it automatically track the value of node_online_map. Thus tasks in the top cpuset will have automatic use of hot plugged memory nodes allowed by their cpuset. [akpm@osdl.org: build fix] [bunk@stusta.de: build fix] Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-08-27[PATCH] cpuset: top_cpuset tracks hotplug changes to cpu_online_mapPaul Jackson
Change the list of cpus allowed to tasks in the top (root) cpuset to dynamically track what cpus are online, using a CPU hotplug notifier. Make this top cpus file read-only. On systems that have cpusets configured in their kernel, but that aren't actively using cpusets (for some distros, this covers the majority of systems) all tasks end up in the top cpuset. If that system does support CPU hotplug, then these tasks cannot make use of CPUs that are added after system boot, because the CPUs are not allowed in the top cpuset. This is a surprising regression over earlier kernels that didn't have cpusets enabled. In order to keep the behaviour of cpusets consistent between systems actively making use of them and systems not using them, this patch changes the behaviour of the 'cpus' file in the top (root) cpuset, making it read only, and making it automatically track the value of cpu_online_map. Thus tasks in the top cpuset will have automatic use of hot plugged CPUs allowed by their cpuset. Thanks to Anton Blanchard and Nathan Lynch for reporting this problem, driving the fix, and earlier versions of this patch. Signed-off-by: Paul Jackson <pj@sgi.com> Cc: Nathan Lynch <ntl@pobox.com> Cc: Anton Blanchard <anton@samba.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-24[PATCH] cpuset memory spread basic implementationPaul Jackson
This patch provides the implementation and cpuset interface for an alternative memory allocation policy that can be applied to certain kinds of memory allocations, such as the page cache (file system buffers) and some slab caches (such as inode caches). The policy is called "memory spreading." If enabled, it spreads out these kinds of memory allocations over all the nodes allowed to a task, instead of preferring to place them on the node where the task is executing. All other kinds of allocations, including anonymous pages for a tasks stack and data regions, are not affected by this policy choice, and continue to be allocated preferring the node local to execution, as modified by the NUMA mempolicy. There are two boolean flag files per cpuset that control where the kernel allocates pages for the file system buffers and related in kernel data structures. They are called 'memory_spread_page' and 'memory_spread_slab'. If the per-cpuset boolean flag file 'memory_spread_page' is set, then the kernel will spread the file system buffers (page cache) evenly over all the nodes that the faulting task is allowed to use, instead of preferring to put those pages on the node where the task is running. If the per-cpuset boolean flag file 'memory_spread_slab' is set, then the kernel will spread some file system related slab caches, such as for inodes and dentries evenly over all the nodes that the faulting task is allowed to use, instead of preferring to put those pages on the node where the task is running. The implementation is simple. Setting the cpuset flags 'memory_spread_page' or 'memory_spread_cache' turns on the per-process flags PF_SPREAD_PAGE or PF_SPREAD_SLAB, respectively, for each task that is in the cpuset or subsequently joins that cpuset. In subsequent patches, the page allocation calls for the affected page cache and slab caches are modified to perform an inline check for these flags, and if set, a call to a new routine cpuset_mem_spread_node() returns the node to prefer for the allocation. The cpuset_mem_spread_node() routine is also simple. It uses the value of a per-task rotor cpuset_mem_spread_rotor to select the next node in the current tasks mems_allowed to prefer for the allocation. This policy can provide substantial improvements for jobs that need to place thread local data on the corresponding node, but that need to access large file system data sets that need to be spread across the several nodes in the jobs cpuset in order to fit. Without this patch, especially for jobs that might have one thread reading in the data set, the memory allocation across the nodes in the jobs cpuset can become very uneven. A couple of Copyright year ranges are updated as well. And a couple of email addresses that can be found in the MAINTAINERS file are removed. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-14[PATCH] Page migration documentation updateChristoph Lameter
Update the documentation for page migration. - Fix up bits and pieces in cpusets.txt - Rework text in vm/page-migration to be clearer and reflect the final version of page migration in 2.6.16. Mention Andi Kleen's numactl package that contains user space tools for page migration via libnuma. Add reference to numa_maps and to the manpage in numactl. - Add todo list for outstanding issues Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-11cpuset two little doc fixesPaul Jackson
Two little cpuset documentation fixes. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-01-08[PATCH] cpuset: remove marker_pid documentationPaul Jackson
Remove documentation for the cpuset 'marker_pid' feature, that was in the patch "cpuset: change marker for relative numbering" That patch was previously pulled from *-mm at my (pj) request. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] cpuset: document additional featuresPaul Jackson
Document the additional cpuset features: notify_on_release marker_pid memory_pressure memory_pressure_enabled Rearrange and improve formatting of existing documentation for cpu_exclusive and mem_exclusive features. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] cpusets: swap migration interfacePaul Jackson
Add a boolean "memory_migrate" to each cpuset, represented by a file containing "0" or "1" in each directory below /dev/cpuset. It defaults to false (file contains "0"). It can be set true by writing "1" to the file. If true, then anytime that a task is attached to the cpuset so marked, the pages of that task will be moved to that cpuset, preserving, to the extent practical, the cpuset-relative placement of the pages. Also anytime that a cpuset so marked has its memory placement changed (by writing to its "mems" file), the tasks in that cpuset will have their pages moved to the cpusets new nodes, preserving, to the extent practical, the cpuset-relative placement of the moved pages. Signed-off-by: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <christoph@lameter.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30[PATCH] Typo fix: explictly -> explicitlyJean Delvare
(akpm: I don't do typo patches, but one of these is in a printk string) Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10[PATCH] Spelling fixes for Documentation/Tobias Klauser
The attached patch fixes the following spelling errors in Documentation/ - double "the" - Several misspellings of function/functionality - infomation - memeory - Recieved - wether and possibly others which I forgot ;-) Trailing whitespaces on the same line as the typo are also deleted. Signed-off-by: Tobias Klauser <tklauser@nuerscht.ch> Signed-off-by: Domen Puncer <domen@coderock.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07[PATCH] cpusets: formalize intermediate GFP_KERNEL containmentPaul Jackson
This patch makes use of the previously underutilized cpuset flag 'mem_exclusive' to provide what amounts to another layer of memory placement resolution. With this patch, there are now the following four layers of memory placement available: 1) The whole system (interrupt and GFP_ATOMIC allocations can use this), 2) The nearest enclosing mem_exclusive cpuset (GFP_KERNEL allocations can use), 3) The current tasks cpuset (GFP_USER allocations constrained to here), and 4) Specific node placement, using mbind and set_mempolicy. These nest - each layer is a subset (same or within) of the previous. Layer (2) above is new, with this patch. The call used to check whether a zone (its node, actually) is in a cpuset (in its mems_allowed, actually) is extended to take a gfp_mask argument, and its logic is extended, in the case that __GFP_HARDWALL is not set in the flag bits, to look up the cpuset hierarchy for the nearest enclosing mem_exclusive cpuset, to determine if placement is allowed. The definition of GFP_USER, which used to be identical to GFP_KERNEL, is changed to also set the __GFP_HARDWALL bit, in the previous cpuset_gfp_hardwall_flag patch. GFP_ATOMIC and GFP_KERNEL allocations will stay within the current tasks cpuset, so long as any node therein is not too tight on memory, but will escape to the larger layer, if need be. The intended use is to allow something like a batch manager to handle several jobs, each job in its own cpuset, but using common kernel memory for caches and such. Swapper and oom_kill activity is also constrained to Layer (2). A task in or below one mem_exclusive cpuset should not cause swapping on nodes in another non-overlapping mem_exclusive cpuset, nor provoke oom_killing of a task in another such cpuset. Heavy use of kernel memory for i/o caching and such by one job should not impact the memory available to jobs in other non-overlapping mem_exclusive cpusets. This patch enables providing hardwall, inescapable cpusets for memory allocations of each job, while sharing kernel memory allocations between several jobs, in an enclosing mem_exclusive cpuset. Like Dinakar's patch earlier to enable administering sched domains using the cpu_exclusive flag, this patch also provides a useful meaning to a cpuset flag that had previously done nothing much useful other than restrict what cpuset configurations were allowed. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25[PATCH] Dynamic sched domains: cpuset changesDinakar Guniguntala
Adds the core update_cpu_domains code and updated cpusets documentation Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com> Acked-by: Paul Jackson <pj@sgi.com> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-20[PATCH] cpusets+hotplug+preepmt brokenPaul Jackson
This patch removes the entwining of cpusets and hotplug code in the "No more Mr. Nice Guy" case of sched.c move_task_off_dead_cpu(). Since the hotplug code is holding a spinlock at this point, we cannot take the cpuset semaphore, cpuset_sem, as would seem to be required either to update the tasks cpuset, or to scan up the nested cpuset chain, looking for the nearest cpuset ancestor that still has some CPUs that are online. So we just punt and blast the tasks cpus_allowed with all bits allowed. This reverts these lines of code to what they were before the cpuset patch. And it updates the cpuset Doc file, to match. The one known alternative to this that seems to work came from Dinakar Guniguntala, and required the hotplug code to take the cpuset_sem semaphore much earlier in its processing. So far as we know, the increased locking entanglement between cpusets and hot plug of this alternative approach is not worth doing in this case. Signed-off-by: Paul Jackson <pj@sgi.com> Acked-by: Nathan Lynch <ntl@pobox.com> Acked-by: Dinakar Guniguntala <dino@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!