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authorRik van Riel <riel@redhat.com>2014-01-27 17:03:40 -0500
committerIngo Molnar <mingo@kernel.org>2014-01-28 13:17:04 +0100
commit52bf84aa206cd2c2516dfa3e03b578edf8a3242f (patch)
treee8acbb2c3ce90b7aed27046c7efc5a082f6ef684 /mm/mempolicy.c
parenta57beec5d427086cdc8d75fd51164577193fa7f4 (diff)
downloadop-kernel-dev-52bf84aa206cd2c2516dfa3e03b578edf8a3242f.zip
op-kernel-dev-52bf84aa206cd2c2516dfa3e03b578edf8a3242f.tar.gz
sched/numa, mm: Remove p->numa_migrate_deferred
Excessive migration of pages can hurt the performance of workloads that span multiple NUMA nodes. However, it turns out that the p->numa_migrate_deferred knob is a really big hammer, which does reduce migration rates, but does not actually help performance. Now that the second stage of the automatic numa balancing code has stabilized, it is time to replace the simplistic migration deferral code with something smarter. Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Chegu Vinod <chegu_vinod@hp.com> Link: http://lkml.kernel.org/r/1390860228-21539-2-git-send-email-riel@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c45
1 files changed, 0 insertions, 45 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 0cd2c4d..68d5c7f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2304,35 +2304,6 @@ static void sp_free(struct sp_node *n)
kmem_cache_free(sn_cache, n);
}
-#ifdef CONFIG_NUMA_BALANCING
-static bool numa_migrate_deferred(struct task_struct *p, int last_cpupid)
-{
- /* Never defer a private fault */
- if (cpupid_match_pid(p, last_cpupid))
- return false;
-
- if (p->numa_migrate_deferred) {
- p->numa_migrate_deferred--;
- return true;
- }
- return false;
-}
-
-static inline void defer_numa_migrate(struct task_struct *p)
-{
- p->numa_migrate_deferred = sysctl_numa_balancing_migrate_deferred;
-}
-#else
-static inline bool numa_migrate_deferred(struct task_struct *p, int last_cpupid)
-{
- return false;
-}
-
-static inline void defer_numa_migrate(struct task_struct *p)
-{
-}
-#endif /* CONFIG_NUMA_BALANCING */
-
/**
* mpol_misplaced - check whether current page node is valid in policy
*
@@ -2435,24 +2406,8 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
*/
last_cpupid = page_cpupid_xchg_last(page, this_cpupid);
if (!cpupid_pid_unset(last_cpupid) && cpupid_to_nid(last_cpupid) != thisnid) {
-
- /* See sysctl_numa_balancing_migrate_deferred comment */
- if (!cpupid_match_pid(current, last_cpupid))
- defer_numa_migrate(current);
-
goto out;
}
-
- /*
- * The quadratic filter above reduces extraneous migration
- * of shared pages somewhat. This code reduces it even more,
- * reducing the overhead of page migrations of shared pages.
- * This makes workloads with shared pages rely more on
- * "move task near its memory", and less on "move memory
- * towards its task", which is exactly what we want.
- */
- if (numa_migrate_deferred(current, last_cpupid))
- goto out;
}
if (curnid != polnid)
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