From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH 22/22] mm, compaction: Capture a page under direct compaction
Date: Thu, 31 Jan 2019 17:11:04 +0100 [thread overview]
Message-ID: <2124d934-0678-6a4b-9991-7450b1e4e39a@suse.cz> (raw)
In-Reply-To: <20190118175136.31341-23-mgorman@techsingularity.net>
On 1/18/19 6:51 PM, Mel Gorman wrote:
> Compaction is inherently race-prone as a suitable page freed during
> compaction can be allocated by any parallel task. This patch uses a
> capture_control structure to isolate a page immediately when it is freed
> by a direct compactor in the slow path of the page allocator. The intent
> is to avoid redundant scanning.
>
> 5.0.0-rc1 5.0.0-rc1
> selective-v3r17 capture-v3r19
> Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
> Amean fault-both-3 2582.11 ( 0.00%) 2563.68 ( 0.71%)
> Amean fault-both-5 4500.26 ( 0.00%) 4233.52 ( 5.93%)
> Amean fault-both-7 5819.53 ( 0.00%) 6333.65 ( -8.83%)
> Amean fault-both-12 9321.18 ( 0.00%) 9759.38 ( -4.70%)
> Amean fault-both-18 9782.76 ( 0.00%) 10338.76 ( -5.68%)
> Amean fault-both-24 15272.81 ( 0.00%) 13379.55 * 12.40%*
> Amean fault-both-30 15121.34 ( 0.00%) 16158.25 ( -6.86%)
> Amean fault-both-32 18466.67 ( 0.00%) 18971.21 ( -2.73%)
>
> Latency is only moderately affected but the devil is in the details.
> A closer examination indicates that base page fault latency is reduced
> but latency of huge pages is increased as it takes creater care to
> succeed. Part of the "problem" is that allocation success rates are close
> to 100% even when under pressure and compaction gets harder
>
> 5.0.0-rc1 5.0.0-rc1
> selective-v3r17 capture-v3r19
> Percentage huge-3 96.70 ( 0.00%) 98.23 ( 1.58%)
> Percentage huge-5 96.99 ( 0.00%) 95.30 ( -1.75%)
> Percentage huge-7 94.19 ( 0.00%) 97.24 ( 3.24%)
> Percentage huge-12 94.95 ( 0.00%) 97.35 ( 2.53%)
> Percentage huge-18 96.74 ( 0.00%) 97.30 ( 0.58%)
> Percentage huge-24 97.07 ( 0.00%) 97.55 ( 0.50%)
> Percentage huge-30 95.69 ( 0.00%) 98.50 ( 2.95%)
> Percentage huge-32 96.70 ( 0.00%) 99.27 ( 2.65%)
>
> And scan rates are reduced as expected by 6% for the migration scanner
> and 29% for the free scanner indicating that there is less redundant work.
>
> Compaction migrate scanned 20815362 19573286
> Compaction free scanned 16352612 11510663
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Nit below:
...
> @@ -819,6 +870,7 @@ static inline void __free_one_page(struct page *page,
> unsigned long uninitialized_var(buddy_pfn);
> struct page *buddy;
> unsigned int max_order;
> + struct capture_control *capc = task_capc(zone);
>
> max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1);
>
> @@ -834,6 +886,12 @@ static inline void __free_one_page(struct page *page,
>
> continue_merging:
> while (order < max_order - 1) {
> + if (compaction_capture(capc, page, order, migratetype)) {
> + if (likely(!is_migrate_isolate(migratetype)))
compaction_capture() won't act on isolated migratetype, so this check is
unnecessary?
> + __mod_zone_freepage_state(zone, -(1 << order),
> + migratetype);
> + return;
> + }
> buddy_pfn = __find_buddy_pfn(pfn, order);
> buddy = page + (buddy_pfn - pfn);
>
next prev parent reply other threads:[~2019-01-31 16:11 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-18 17:51 [PATCH 00/22] Increase success rates and reduce latency of compaction v3 Mel Gorman
2019-01-18 17:51 ` [PATCH 01/22] mm, compaction: Shrink compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 02/22] mm, compaction: Rearrange compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 03/22] mm, compaction: Remove last_migrated_pfn from compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 04/22] mm, compaction: Remove unnecessary zone parameter in some instances Mel Gorman
2019-01-18 17:51 ` [PATCH 05/22] mm, compaction: Rename map_pages to split_map_pages Mel Gorman
2019-01-18 17:51 ` [PATCH 06/22] mm, migrate: Immediately fail migration of a page with no migration handler Mel Gorman
2019-01-18 17:51 ` [PATCH 07/22] mm, compaction: Always finish scanning of a full pageblock Mel Gorman
2019-01-18 17:51 ` [PATCH 08/22] mm, compaction: Ignore the fragmentation avoidance boost for isolation and compaction Mel Gorman
2019-01-18 17:51 ` [PATCH 09/22] mm, compaction: Use free lists to quickly locate a migration source Mel Gorman
2019-01-31 13:55 ` Vlastimil Babka
2019-01-31 14:12 ` Vlastimil Babka
2019-02-01 15:06 ` Mel Gorman
2019-02-04 8:55 ` [PATCH] mm, compaction: Use free lists to quickly locate a migration source -fix Mel Gorman
2019-02-08 17:10 ` [PATCH 09/22] mm, compaction: Use free lists to quickly locate a migration source Vlastimil Babka
2019-01-18 17:51 ` [PATCH 10/22] mm, compaction: Keep migration source private to a single compaction instance Mel Gorman
2019-01-18 17:51 ` [PATCH 11/22] mm, compaction: Use free lists to quickly locate a migration target Mel Gorman
2019-01-31 14:52 ` Vlastimil Babka
2019-02-01 14:51 ` Mel Gorman
2019-02-01 14:58 ` Vlastimil Babka
2019-02-04 12:01 ` [PATCH] mm, compaction: Use free lists to quickly locate a migration source -fix Mel Gorman
2021-01-12 5:19 ` [PATCH] mm, compaction: make sure we isolate a valid freepage when high_pfn is used Rokudo Yan
2021-01-12 9:10 ` Mel Gorman
2021-01-12 9:47 ` [PATCH] mm, compaction: move high_pfn to the for loop scope Rokudo Yan
2021-01-12 10:45 ` Mel Gorman
2021-01-12 10:48 ` Vlastimil Babka
2021-01-12 22:27 ` Andrew Morton
2021-01-18 7:41 ` Rokudo Yan
2021-01-18 9:42 ` Mel Gorman
2019-01-18 17:51 ` [PATCH 12/22] mm, compaction: Avoid rescanning the same pageblock multiple times Mel Gorman
2019-01-18 17:51 ` [PATCH 13/22] mm, compaction: Finish pageblock scanning on contention Mel Gorman
2019-01-18 17:51 ` [PATCH 14/22] mm, compaction: Check early for huge pages encountered by the migration scanner Mel Gorman
2019-01-18 17:51 ` [PATCH 15/22] mm, compaction: Keep cached migration PFNs synced for unusable pageblocks Mel Gorman
2019-01-18 17:51 ` [PATCH 16/22] mm, compaction: Rework compact_should_abort as compact_check_resched Mel Gorman
2019-01-18 17:51 ` [PATCH 17/22] mm, compaction: Do not consider a need to reschedule as contention Mel Gorman
2019-01-18 17:51 ` [PATCH 18/22] mm, compaction: Reduce premature advancement of the migration target scanner Mel Gorman
2019-01-18 17:51 ` [PATCH 19/22] mm, compaction: Round-robin the order while searching the free lists for a target Mel Gorman
2019-01-18 17:51 ` [PATCH 20/22] mm, compaction: Sample pageblocks for free pages Mel Gorman
2019-01-31 15:39 ` Vlastimil Babka
2019-01-18 17:51 ` [PATCH 21/22] mm, compaction: Be selective about what pageblocks to clear skip hints Mel Gorman
2019-01-31 15:45 ` Vlastimil Babka
2019-01-18 17:51 ` [PATCH 22/22] mm, compaction: Capture a page under direct compaction Mel Gorman
2019-01-31 16:11 ` Vlastimil Babka [this message]
2019-02-01 14:38 ` [PATCH] mm, compaction: Capture a page under direct compaction -fix Mel Gorman
2019-01-24 8:53 ` [PATCH 00/22] Increase success rates and reduce latency of compaction v3 Mel Gorman
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