From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
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 11/22] mm, compaction: Use free lists to quickly locate a migration target
Date: Fri, 1 Feb 2019 15:58:19 +0100 [thread overview]
Message-ID: <cb0bae2e-8628-1378-68a1-9da02a94652e@suse.cz> (raw)
In-Reply-To: <20190201145139.GI9565@techsingularity.net>
On 2/1/19 3:51 PM, Mel Gorman wrote:
> On Thu, Jan 31, 2019 at 03:52:10PM +0100, Vlastimil Babka wrote:
>>> -/* Reorder the free list to reduce repeated future searches */
>>> +/*
>>> + * Used when scanning for a suitable migration target which scans freelists
>>> + * in reverse. Reorders the list such as the unscanned pages are scanned
>>> + * first on the next iteration of the free scanner
>>> + */
>>> +static void
>>> +move_freelist_head(struct list_head *freelist, struct page *freepage)
>>> +{
>>> + LIST_HEAD(sublist);
>>> +
>>> + if (!list_is_last(freelist, &freepage->lru)) {
>>
>> Shouldn't there be list_is_first() for symmetry?
>>
>
> I don't think it would help. We're reverse traversing the list when this is
> called. If it's the last entry, it's moving just one page before breaking
> off the search and a shuffle has minimal impact. If it's the first page
> then list_cut_before moves the entire list to sublist before splicing it
> back so it's a pointless operation.
Yeah I thought the goal was to avoid the pointless operation, which is
why it was previously added as "if (!list_is_last())" in
move_freelist_head(). So in move_freelist_head() it would have to be as
"if (!list_is_first())" to achieve the same effect. Agree that it's
marginal but if that's so then I would just remove the checks completely
(from both functions) instead of having it subtly wrong in one of them?
next prev parent reply other threads:[~2019-02-01 14:58 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=cb0bae2e-8628-1378-68a1-9da02a94652e@suse.cz \
--to=vbabka@suse.cz \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=rientjes@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).