linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Vlastimil Babka <vbabka@suse.cz>
To: Eric Dumazet <edumazet@google.com>
Cc: kernel test robot <oliver.sang@intel.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	0day robot <lkp@intel.com>, Michal Hocko <mhocko@kernel.org>,
	Shakeel Butt <shakeelb@google.com>, Wei Xu <weixugc@google.com>,
	Greg Thelen <gthelen@google.com>, Hugh Dickins <hughd@google.com>,
	David Rientjes <rientjes@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	lkp@lists.01.org, "Huang, Ying" <ying.huang@intel.com>,
	"Tang, Feng" <feng.tang@intel.com>,
	zhengjun.xing@linux.intel.com, fengwei.yin@intel.com,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [mm/page_alloc] 8212a964ee: vm-scalability.throughput 30.5% improvement
Date: Mon, 14 Mar 2022 10:09:10 +0100	[thread overview]
Message-ID: <b3575a73-384c-e0da-1db9-bad2aec053c4@suse.cz> (raw)
In-Reply-To: <CANn89iJwBe4+C8KP--c_9O6QE_Tou+1Z0+ugtuniG-06nzxPmg@mail.gmail.com>

On 3/13/22 22:10, Eric Dumazet wrote:
> On Sun, Mar 13, 2022 at 1:29 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>>
>> On 3/13/22 00:26, Eric Dumazet wrote:
>> > On Sat, Mar 12, 2022 at 10:59 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>> >>
>> >> On 3/12/22 16:43, kernel test robot wrote:
>> >>>
>> >>>
>> >>> Greeting,
>> >>>
>> >>> FYI, we noticed a 30.5% improvement of vm-scalability.throughput due to commit:
>> >>>
>> >>>
>> >>> commit: 8212a964ee020471104e34dce7029dec33c218a9 ("Re: [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held")
>> >>> url: https://github.com/0day-ci/linux/commits/Mel-Gorman/Re-PATCH-v2-mm-page_alloc-call-check_new_pages-while-zone-spinlock-is-not-held/20220309-203504
>> >>> patch link: https://lore.kernel.org/lkml/20220309123245.GI15701@techsingularity.net
>> >>
>> >> Heh, that's weird. I would expect some improvement from Eric's patch,
>> >> but this seems to be actually about Mel's "mm/page_alloc: check
>> >> high-order pages for corruption during PCP operations" applied directly
>> >> on 5.17-rc7 per the github url above. This was rather expected to make
>> >> performance worse if anything, so maybe the improvement is due to some
>> >> unexpected side-effect of different inlining decisions or cache alignment...
>> >>
>> >
>> > I doubt this has anything to do with inlining or cache alignment.
>> >
>> > I am not familiar with the benchmark, but its name
>> > (anon-w-rand-hugetlb) hints at hugetlb ?
>> >
>> > After Mel fix, we go over 512 'struct page' to perform sanity checks,
>> > thus loading into cpu caches the 512 cache lines.
>>
>> Ah, that's true.
>>
>> > This caching is done while no lock is held.
>>
>> But I don't think this is. The test was AFAICS done without your patch,
>> so the lock is still held in rmqueue(). And it's also held in
>> rmqueue_bulk() -> check_pcp_refill().
> 
> Note that Mel patch  touches both check_pcp_refill() and check_new_pcp()
> 
> __rmqueue_pcplist() definitely calls check_new_pcp() while the zone
> spinlock is _not_ held.

Yes, but the checking from check_new_pcp() is active only with
CONFIG_DEBUG_VM or enabled debug_pagealloc, which were both disabled in the
robot's report.

> Note that it is possible to defer calls to check_pcp_refill after the
> spinlock is released.
> 
> Untested patch:

I'll check the latest posting.

  parent reply	other threads:[~2022-03-14  9:09 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-04 17:02 [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held Eric Dumazet
2022-03-04 19:19 ` Shakeel Butt
2022-03-06 22:15 ` David Rientjes
2022-03-07  9:15 ` Mel Gorman
2022-03-08 23:49   ` Eric Dumazet
2022-03-09 12:32     ` Mel Gorman
2022-03-09 17:32       ` Eric Dumazet
2022-03-12 15:43       ` [mm/page_alloc] 8212a964ee: vm-scalability.throughput 30.5% improvement kernel test robot
2022-03-12 18:58         ` Vlastimil Babka
2022-03-12 23:26           ` Eric Dumazet
2022-03-13  9:28             ` Vlastimil Babka
2022-03-13 21:10               ` Eric Dumazet
2022-03-13 21:18                 ` Matthew Wilcox
2022-03-13 21:27                   ` Eric Dumazet
2022-03-13 21:36                     ` Eric Dumazet
2022-03-14  9:09                 ` Vlastimil Babka [this message]
2022-03-07  9:24 ` [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held Vlastimil Babka

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=b3575a73-384c-e0da-1db9-bad2aec053c4@suse.cz \
    --to=vbabka@suse.cz \
    --cc=akpm@linux-foundation.org \
    --cc=edumazet@google.com \
    --cc=eric.dumazet@gmail.com \
    --cc=feng.tang@intel.com \
    --cc=fengwei.yin@intel.com \
    --cc=gthelen@google.com \
    --cc=hughd@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=lkp@intel.com \
    --cc=lkp@lists.01.org \
    --cc=mgorman@techsingularity.net \
    --cc=mhocko@kernel.org \
    --cc=oliver.sang@intel.com \
    --cc=rientjes@google.com \
    --cc=shakeelb@google.com \
    --cc=weixugc@google.com \
    --cc=ying.huang@intel.com \
    --cc=zhengjun.xing@linux.intel.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).