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Groups > linux.kernel > #1590434
| From | Michal Hocko <mhocko@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 9/9] mm: remove unnecessary back-off function when retrying page reclaim |
| Date | 2017-03-01 16:50 +0100 |
| Message-ID | <tgeFR-55d-29@gated-at.bofh.it> (permalink) |
| References | <tfZQt-2Vc-9@gated-at.bofh.it> <tgcXn-3Po-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue 28-02-17 16:40:07, Johannes Weiner wrote: > The backoff mechanism is not needed. If we have MAX_RECLAIM_RETRIES > loops without progress, we'll OOM anyway; backing off might cut one or > two iterations off that in the rare OOM case. If we have intermittent > success reclaiming a few pages, the backoff function gets reset also, > and so is of little help in these scenarios. Yes, as already mentioned elsewhere the original intention was to a more graceful oom convergence when we are trashing over last few reclaimable pages but as the code evolved the result is not all that great. > We might want a backoff function for when there IS progress, but not > enough to be satisfactory. But this isn't that. Remove it. Completely agreed. > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/page_alloc.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 9ac639864bed..223644afed28 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3511,11 +3511,10 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask) > /* > * Checks whether it makes sense to retry the reclaim to make a forward progress > * for the given allocation request. > - * The reclaim feedback represented by did_some_progress (any progress during > - * the last reclaim round) and no_progress_loops (number of reclaim rounds without > - * any progress in a row) is considered as well as the reclaimable pages on the > - * applicable zone list (with a backoff mechanism which is a function of > - * no_progress_loops). > + * > + * We give up when we either have tried MAX_RECLAIM_RETRIES in a row > + * without success, or when we couldn't even meet the watermark if we > + * reclaimed all remaining pages on the LRU lists. > * > * Returns true if a retry is viable or false to enter the oom path. > */ > @@ -3560,13 +3559,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order, > bool wmark; > > available = reclaimable = zone_reclaimable_pages(zone); > - available -= DIV_ROUND_UP((*no_progress_loops) * available, > - MAX_RECLAIM_RETRIES); > available += zone_page_state_snapshot(zone, NR_FREE_PAGES); > > /* > - * Would the allocation succeed if we reclaimed the whole > - * available? > + * Would the allocation succeed if we reclaimed all > + * reclaimable pages? > */ > wmark = __zone_watermark_ok(zone, order, min_wmark, > ac_classzone_idx(ac), alloc_flags, available); > -- > 2.11.1 -- Michal Hocko SUSE Labs
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[PATCH 0/9] mm: kswapd spinning on unreclaimable nodes - fixes and cleanups Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 01:00 +0100
[PATCH 4/9] mm: remove unnecessary reclaimability check from NUMA balancing target Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 01:10 +0100
Re: [PATCH 4/9] mm: remove unnecessary reclaimability check from NUMA balancing target Michal Hocko <mhocko@kernel.org> - 2017-03-01 20:30 +0100
Re: [PATCH 4/9] mm: remove unnecessary reclaimability check from NUMA balancing target "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:40 +0100
[PATCH 8/9] Revert "mm, vmscan: account for skipped pages as a partial scan" Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 01:10 +0100
Re: [PATCH 8/9] Revert "mm, vmscan: account for skipped pages as a partial scan" Michal Hocko <mhocko@kernel.org> - 2017-03-01 17:00 +0100
[PATCH 3/9] mm: remove seemingly spurious reclaimability check from laptop_mode gating Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
Re: [PATCH 3/9] mm: remove seemingly spurious reclaimability check from laptop_mode gating Mel Gorman <mgorman@suse.de> - 2017-03-01 16:20 +0100
Re: [PATCH 3/9] mm: remove seemingly spurious reclaimability check from laptop_mode gating Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:50 +0100
Re: [PATCH 3/9] mm: remove seemingly spurious reclaimability check from laptop_mode gating "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:30 +0100
[PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Michal Hocko <mhocko@kernel.org> - 2017-03-01 17:00 +0100
Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 19:30 +0100
Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim Michal Hocko <mhocko@kernel.org> - 2017-03-01 20:20 +0100
Re: [PATCH 6/9] mm: don't avoid high-priority reclaim on memcg limit reclaim "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:40 +0100
[PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
Re: [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:10 +0100
Re: [PATCH 2/9] mm: fix check for reclaimable pages in PF_MEMALLOC reclaim throttling "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:30 +0100
[PATCH 7/9] mm: delete NR_PAGES_SCANNED and pgdat_reclaimable() Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
Re: [PATCH 7/9] mm: delete NR_PAGES_SCANNED and pgdat_reclaimable() Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:50 +0100
[PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 09:00 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-02 04:30 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Shakeel Butt <shakeelb@google.com> - 2017-03-03 02:40 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Minchan Kim <minchan@kernel.org> - 2017-03-03 02:50 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Michal Hocko <mhocko@kernel.org> - 2017-03-03 09:10 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Minchan Kim <minchan@kernel.org> - 2017-03-06 02:40 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-06 17:40 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2017-03-07 02:10 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Minchan Kim <minchan@kernel.org> - 2017-03-07 08:50 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Michal Hocko <mhocko@kernel.org> - 2017-03-07 11:30 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-07 20:00 +0100
Re: [PATCH 1/9] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes Mel Gorman <mgorman@suse.de> - 2017-03-09 15:40 +0100
[PATCH 9/9] mm: remove unnecessary back-off function when retrying page reclaim Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 15:00 +0100
Re: [PATCH 9/9] mm: remove unnecessary back-off function when retrying page reclaim Michal Hocko <mhocko@kernel.org> - 2017-03-01 16:50 +0100
[PATCH 5/9] mm: don't avoid high-priority reclaim on unreclaimable nodes Johannes Weiner <hannes@cmpxchg.org> - 2017-03-01 15:00 +0100
Re: [PATCH 5/9] mm: don't avoid high-priority reclaim on unreclaimable nodes Michal Hocko <mhocko@kernel.org> - 2017-03-01 17:00 +0100
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