On 09/22/2016 04:52 PM, Michal Hocko wrote:
> On Thu 22-09-16 16:08:21, Michal Hocko wrote:
>> On Thu 22-09-16 14:51:48, Vlastimil Babka wrote:
>> > >From 465e1bd61b7a6d6901a44f09b1a76514dbc220fa Mon Sep 17 00:00:00 2001
>> > From: Vlastimil Babka <vba...@suse.cz>
>> > Date: Thu, 22 Sep 2016 13:54:32 +0200
>> > Subject: [PATCH] mm, compaction: more reliably increase direct compaction
>> >  priority-fix
>> > 
>> > When increasing the compaction priority, also reset retries. Otherwise we 
>> > can
>> > consume all retries on the lower priorities.
>> 
>> OK, this is an improvement. I am just thinking that we might want to
>> pull
>>      if (order && compaction_made_progress(compact_result))
>>              compaction_retries++;
>> 
>> into should_compact_retry as well. I've had it there originally because
>> it was in line with no_progress_loops but now that we have compaction
>> priorities it would fit into retry logic better. As a plus it would
>> count only those compaction rounds where we we didn't have to rely on
>                                                  did that should be
> 
>> the compaction retry logic. What do you think?

In that case I would also add this for consistency?

----8<----
>From a7921e57ba1189b9c08fc4879358a908c390e47c Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vba...@suse.cz>
Date: Thu, 22 Sep 2016 17:02:37 +0200
Subject: [PATCH] mm, page_alloc: pull no_progress_loops update to
 should_reclaim_retry()

The should_reclaim_retry() makes decisions based on no_progress_loops, so it
makes sense to also update the counter there. It will be also consistent with
should_compact_retry() and compaction_retries. No functional change.

Signed-off-by: Vlastimil Babka <vba...@suse.cz>
---
 mm/page_alloc.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 582820080601..a01359ab3ed6 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3401,16 +3401,26 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
 static inline bool
 should_reclaim_retry(gfp_t gfp_mask, unsigned order,
                     struct alloc_context *ac, int alloc_flags,
-                    bool did_some_progress, int no_progress_loops)
+                    bool did_some_progress, int *no_progress_loops)
 {
        struct zone *zone;
        struct zoneref *z;
 
        /*
+        * Costly allocations might have made a progress but this doesn't mean
+        * their order will become available due to high fragmentation so
+        * always increment the no progress counter for them
+        */
+       if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
+               no_progress_loops = 0;
+       else
+               no_progress_loops++;
+
+       /*
         * Make sure we converge to OOM if we cannot make any progress
         * several times in the row.
         */
-       if (no_progress_loops > MAX_RECLAIM_RETRIES)
+       if (*no_progress_loops > MAX_RECLAIM_RETRIES)
                return false;
 
        /*
@@ -3425,7 +3435,7 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
                unsigned long reclaimable;
 
                available = reclaimable = zone_reclaimable_pages(zone);
-               available -= DIV_ROUND_UP(no_progress_loops * available,
+               available -= DIV_ROUND_UP((*no_progress_loops) * available,
                                          MAX_RECLAIM_RETRIES);
                available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
 
@@ -3641,18 +3651,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int 
order,
        if (order > PAGE_ALLOC_COSTLY_ORDER && !(gfp_mask & __GFP_REPEAT))
                goto nopage;
 
-       /*
-        * Costly allocations might have made a progress but this doesn't mean
-        * their order will become available due to high fragmentation so
-        * always increment the no progress counter for them
-        */
-       if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER)
-               no_progress_loops = 0;
-       else
-               no_progress_loops++;
-
        if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
-                                did_some_progress > 0, no_progress_loops))
+                                did_some_progress > 0, &no_progress_loops))
                goto retry;
 
        /*
-- 
2.10.0



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