From: Vlastimil Babka <vbabka@suse.cz> To: Mel Gorman <mgorman@techsingularity.net>, Andrew Morton <akpm@linux-foundation.org> Cc: Linux-MM <linux-mm@kvack.org>, Linux-FSDevel <linux-fsdevel@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, Jan Kara <jack@suse.cz>, Andi Kleen <ak@linux.intel.com>, Dave Hansen <dave.hansen@intel.com>, Dave Chinner <david@fromorbit.com> Subject: Re: [PATCH 4/8] mm: Only drain per-cpu pagevecs once per pagevec usage Date: Thu, 19 Oct 2017 11:12:52 +0200 Message-ID: <a9f2fc7c-906d-a49e-8e8f-d1024dc754ac@suse.cz> (raw) In-Reply-To: <20171018075952.10627-5-mgorman@techsingularity.net> On 10/18/2017 09:59 AM, Mel Gorman wrote: > When a pagevec is initialised on the stack, it is generally used multiple > times over a range of pages, looking up entries and then releasing them. > On each pagevec_release, the per-cpu deferred LRU pagevecs are drained > on the grounds the page being released may be on those queues and the > pages may be cache hot. In many cases only the first drain is necessary > as it's unlikely that the range of pages being walked is racing against > LRU addition. Even if there is such a race, the impact is marginal where > as constantly redraining the lru pagevecs costs. Right, the drain is only to a local cpu, not all of them, so that kind of "racing" shouldn't be even possible. > This patch ensures that pagevec is only drained once in a given lifecycle > without increasing the cache footprint of the pagevec structure. Only Well, strictly speaking it does prevent decreasing the cache footprint by removing the 'cold' field later :) > sparsetruncate tiny is shown here as large files have many exceptional > entries and calls pagecache_release less frequently. > > sparsetruncate (tiny) > 4.14.0-rc4 4.14.0-rc4 > batchshadow-v1r1 onedrain-v1r1 > Min Time 141.00 ( 0.00%) 141.00 ( 0.00%) > 1st-qrtle Time 142.00 ( 0.00%) 142.00 ( 0.00%) > 2nd-qrtle Time 142.00 ( 0.00%) 142.00 ( 0.00%) > 3rd-qrtle Time 143.00 ( 0.00%) 143.00 ( 0.00%) > Max-90% Time 144.00 ( 0.00%) 144.00 ( 0.00%) > Max-95% Time 146.00 ( 0.00%) 145.00 ( 0.68%) > Max-99% Time 198.00 ( 0.00%) 194.00 ( 2.02%) > Max Time 254.00 ( 0.00%) 208.00 ( 18.11%) > Amean Time 145.12 ( 0.00%) 144.30 ( 0.56%) > Stddev Time 12.74 ( 0.00%) 9.62 ( 24.49%) > Coeff Time 8.78 ( 0.00%) 6.67 ( 24.06%) > Best99%Amean Time 144.29 ( 0.00%) 143.82 ( 0.32%) > Best95%Amean Time 142.68 ( 0.00%) 142.31 ( 0.26%) > Best90%Amean Time 142.52 ( 0.00%) 142.19 ( 0.24%) > Best75%Amean Time 142.26 ( 0.00%) 141.98 ( 0.20%) > Best50%Amean Time 141.90 ( 0.00%) 141.71 ( 0.13%) > Best25%Amean Time 141.80 ( 0.00%) 141.43 ( 0.26%) > > The impact on bonnie is marginal and within the noise because a significant > percentage of the file being truncated has been reclaimed and consists of > shadow entries which reduce the hotness of the pagevec_release path. > > Signed-off-by: Mel Gorman <mgorman@techsingularity.net> > --- > include/linux/pagevec.h | 4 +++- > mm/swap.c | 5 ++++- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h > index 4dcd5506f1ed..4231979be982 100644 > --- a/include/linux/pagevec.h > +++ b/include/linux/pagevec.h > @@ -16,7 +16,8 @@ struct address_space; > > struct pagevec { > unsigned long nr; > - unsigned long cold; > + bool cold; > + bool drained; 'drained' sounds a bit misleading to me, I would expect it to refer to *this* pagevec. What about e.g. "lru_drained"? Thanks > struct page *pages[PAGEVEC_SIZE]; > }; > > @@ -45,6 +46,7 @@ static inline void pagevec_init(struct pagevec *pvec, int cold) > { > pvec->nr = 0; > pvec->cold = cold; > + pvec->drained = false; > } > > static inline void pagevec_reinit(struct pagevec *pvec) > diff --git a/mm/swap.c b/mm/swap.c > index a77d68f2c1b6..31bd9d8a5db7 100644 > --- a/mm/swap.c > +++ b/mm/swap.c > @@ -833,7 +833,10 @@ EXPORT_SYMBOL(release_pages); > */ > void __pagevec_release(struct pagevec *pvec) > { > - lru_add_drain(); > + if (!pvec->drained) { > + lru_add_drain(); > + pvec->drained = true; > + } > release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); > pagevec_reinit(pvec); > } > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply index Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-10-18 7:59 [PATCH 0/8] Follow-up for speed up page cache truncation v2 Mel Gorman 2017-10-18 7:59 ` [PATCH 1/8] mm, page_alloc: Enable/disable IRQs once when freeing a list of pages Mel Gorman 2017-10-18 9:02 ` Vlastimil Babka 2017-10-18 10:15 ` Mel Gorman 2017-10-18 7:59 ` [PATCH 2/8] mm, truncate: Do not check mapping for every page being truncated Mel Gorman 2017-10-19 8:11 ` Jan Kara 2017-10-18 7:59 ` [PATCH 3/8] mm, truncate: Remove all exceptional entries from pagevec under one lock Mel Gorman 2017-10-18 7:59 ` [PATCH 4/8] mm: Only drain per-cpu pagevecs once per pagevec usage Mel Gorman 2017-10-19 9:12 ` Vlastimil Babka [this message] 2017-10-19 9:33 ` Mel Gorman 2017-10-19 13:21 ` Vlastimil Babka 2017-10-18 7:59 ` [PATCH 5/8] mm, pagevec: Remove cold parameter for pagevecs Mel Gorman 2017-10-19 9:24 ` Vlastimil Babka 2017-10-18 7:59 ` [PATCH 6/8] mm: Remove cold parameter for release_pages Mel Gorman 2017-10-19 9:26 ` Vlastimil Babka 2017-10-18 7:59 ` [PATCH 7/8] mm, Remove cold parameter from free_hot_cold_page* Mel Gorman 2017-10-19 13:12 ` Vlastimil Babka 2017-10-19 15:43 ` Mel Gorman 2017-10-18 7:59 ` [PATCH 8/8] mm: Remove __GFP_COLD Mel Gorman 2017-10-19 13:18 ` Vlastimil Babka 2017-10-19 13:42 ` Vlastimil Babka 2017-10-19 14:32 ` Mel Gorman -- strict thread matches above, loose matches on Subject: below -- 2017-10-12 9:30 [PATCH 0/8] Follow-up for speed up page cache truncation Mel Gorman 2017-10-12 9:30 ` [PATCH 4/8] mm: Only drain per-cpu pagevecs once per pagevec usage Mel Gorman
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