diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2011-07-28 10:43:51 +0200 |
|---|---|---|
| committer | Clark Williams <williams@redhat.com> | 2011-12-28 16:25:50 -0600 |
| commit | 6539c3c62945d3340544bc45dc112714e2427d54 (patch) | |
| tree | bea549695e8ef7b5151f6ab930a2d78bfeb0a105 /arch | |
| parent | 6ad41c0062520a65be3a1127bf5256cb1be78e05 (diff) | |
mm, rt: kmap_atomic scheduling
In fact, with migrate_disable() existing one could play games with
kmap_atomic. You could save/restore the kmap_atomic slots on context
switch (if there are any in use of course), this should be esp easy now
that we have a kmap_atomic stack.
Something like the below.. it wants replacing all the preempt_disable()
stuff with pagefault_disable() && migrate_disable() of course, but then
you can flip kmaps around like below.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
[dvhart@linux.intel.com: build fix]
Link: http://lkml.kernel.org/r/1311842631.5890.208.camel@twins
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/process_32.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 1a61ad20f3b0..055a0cc50342 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -39,6 +39,7 @@ #include <linux/io.h> #include <linux/kdebug.h> #include <linux/cpuidle.h> +#include <linux/highmem.h> #include <asm/pgtable.h> #include <asm/system.h> @@ -350,6 +351,41 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT)) __switch_to_xtra(prev_p, next_p, tss); +#if defined CONFIG_PREEMPT_RT_FULL && defined CONFIG_HIGHMEM + /* + * Save @prev's kmap_atomic stack + */ + prev_p->kmap_idx = __this_cpu_read(__kmap_atomic_idx); + if (unlikely(prev_p->kmap_idx)) { + int i; + + for (i = 0; i < prev_p->kmap_idx; i++) { + int idx = i + KM_TYPE_NR * smp_processor_id(); + + pte_t *ptep = kmap_pte - idx; + prev_p->kmap_pte[i] = *ptep; + kpte_clear_flush(ptep, __fix_to_virt(FIX_KMAP_BEGIN + idx)); + } + + __this_cpu_write(__kmap_atomic_idx, 0); + } + + /* + * Restore @next_p's kmap_atomic stack + */ + if (unlikely(next_p->kmap_idx)) { + int i; + + __this_cpu_write(__kmap_atomic_idx, next_p->kmap_idx); + + for (i = 0; i < next_p->kmap_idx; i++) { + int idx = i + KM_TYPE_NR * smp_processor_id(); + + set_pte(kmap_pte - idx, next_p->kmap_pte[i]); + } + } +#endif + /* If we're going to preload the fpu context, make sure clts is run while we're batching the cpu state updates. */ if (preload_fpu) |