diff options
author | Seth Jennings <sjenning@linux.vnet.ibm.com> | 2011-10-12 14:41:00 -0500 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-10-17 15:24:11 -0700 |
commit | 00bf256011d362e7d61824f3cda8514f5d48585d (patch) | |
tree | c76261e9e4d023628673253f74648504295274ed /drivers | |
parent | 3b769edd58371fb70417c3f43c6d4a2da075703a (diff) | |
download | linux-00bf256011d362e7d61824f3cda8514f5d48585d.tar.bz2 |
staging: zcache: remove zcache_direct_reclaim_lock
zcache_do_preload() currently does a spin_trylock() on the
zcache_direct_reclaim_lock. Holding this lock intends to prevent
shrink_zcache_memory() from evicting zbud pages as a result
of a preload.
However, it also prevents two threads from
executing zcache_do_preload() at the same time. The first
thread will obtain the lock and the second thread's spin_trylock()
will fail (an aborted preload) causing the page to be either lost
(cleancache) or pushed out to the swap device (frontswap). It
also doesn't ensure that the call to shrink_zcache_memory() is
on the same thread as the call to zcache_do_preload().
Additional, there is no need for this mechanism because all
zcache_do_preload() calls that come down from cleancache already
have PF_MEMALLOC set in the process flags which prevents
direct reclaim in the memory manager. If the zcache_do_preload()
call is done from the frontswap path, we _want_ reclaim to be
done (which it isn't right now).
This patch removes the zcache_direct_reclaim_lock and related
statistics in zcache.
Based on v3.1-rc8
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Reviewed-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/staging/zcache/zcache-main.c | 31 |
1 files changed, 4 insertions, 27 deletions
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c index 22b0a7506496..3768bf2e8d91 100644 --- a/drivers/staging/zcache/zcache-main.c +++ b/drivers/staging/zcache/zcache-main.c @@ -962,15 +962,6 @@ out: static unsigned long zcache_failed_get_free_pages; static unsigned long zcache_failed_alloc; static unsigned long zcache_put_to_flush; -static unsigned long zcache_aborted_preload; -static unsigned long zcache_aborted_shrink; - -/* - * Ensure that memory allocation requests in zcache don't result - * in direct reclaim requests via the shrinker, which would cause - * an infinite loop. Maybe a GFP flag would be better? - */ -static DEFINE_SPINLOCK(zcache_direct_reclaim_lock); /* * for now, used named slabs so can easily track usage; later can @@ -1009,10 +1000,6 @@ static int zcache_do_preload(struct tmem_pool *pool) goto out; if (unlikely(zcache_obj_cache == NULL)) goto out; - if (!spin_trylock(&zcache_direct_reclaim_lock)) { - zcache_aborted_preload++; - goto out; - } preempt_disable(); kp = &__get_cpu_var(zcache_preloads); while (kp->nr < ARRAY_SIZE(kp->objnodes)) { @@ -1021,7 +1008,7 @@ static int zcache_do_preload(struct tmem_pool *pool) ZCACHE_GFP_MASK); if (unlikely(objnode == NULL)) { zcache_failed_alloc++; - goto unlock_out; + goto out; } preempt_disable(); kp = &__get_cpu_var(zcache_preloads); @@ -1034,13 +1021,13 @@ static int zcache_do_preload(struct tmem_pool *pool) obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK); if (unlikely(obj == NULL)) { zcache_failed_alloc++; - goto unlock_out; + goto out; } page = (void *)__get_free_page(ZCACHE_GFP_MASK); if (unlikely(page == NULL)) { zcache_failed_get_free_pages++; kmem_cache_free(zcache_obj_cache, obj); - goto unlock_out; + goto out; } preempt_disable(); kp = &__get_cpu_var(zcache_preloads); @@ -1053,8 +1040,6 @@ static int zcache_do_preload(struct tmem_pool *pool) else free_page((unsigned long)page); ret = 0; -unlock_out: - spin_unlock(&zcache_direct_reclaim_lock); out: return ret; } @@ -1429,8 +1414,6 @@ ZCACHE_SYSFS_RO(evicted_buddied_pages); ZCACHE_SYSFS_RO(failed_get_free_pages); ZCACHE_SYSFS_RO(failed_alloc); ZCACHE_SYSFS_RO(put_to_flush); -ZCACHE_SYSFS_RO(aborted_preload); -ZCACHE_SYSFS_RO(aborted_shrink); ZCACHE_SYSFS_RO(compress_poor); ZCACHE_SYSFS_RO(mean_compress_poor); ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_raw_pages); @@ -1472,8 +1455,6 @@ static struct attribute *zcache_attrs[] = { &zcache_failed_get_free_pages_attr.attr, &zcache_failed_alloc_attr.attr, &zcache_put_to_flush_attr.attr, - &zcache_aborted_preload_attr.attr, - &zcache_aborted_shrink_attr.attr, &zcache_zbud_unbuddied_list_counts_attr.attr, &zcache_zbud_cumul_chunk_counts_attr.attr, &zcache_zv_curr_dist_counts_attr.attr, @@ -1513,11 +1494,7 @@ static int shrink_zcache_memory(struct shrinker *shrink, if (!(gfp_mask & __GFP_FS)) /* does this case really need to be skipped? */ goto out; - if (spin_trylock(&zcache_direct_reclaim_lock)) { - zbud_evict_pages(nr); - spin_unlock(&zcache_direct_reclaim_lock); - } else - zcache_aborted_shrink++; + zbud_evict_pages(nr); } ret = (int)atomic_read(&zcache_zbud_curr_raw_pages); out: |