linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Waiman Long <longman@redhat.com>
To: "ying.huang@intel.com" <ying.huang@intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will@kernel.org>
Cc: Aaron Lu <aaron.lu@intel.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	kernel test robot <oliver.sang@intel.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	lkp@lists.01.org, kernel test robot <lkp@intel.com>,
	Feng Tang <feng.tang@intel.com>,
	Zhengjun Xing <zhengjun.xing@linux.intel.com>,
	fengwei.yin@intel.com
Subject: Re: [mm/page_alloc] f26b3fa046: netperf.Throughput_Mbps -18.0% regression
Date: Tue, 10 May 2022 22:06:46 -0400	[thread overview]
Message-ID: <e3d60afb-b761-ef91-f73d-5fadc32050d5@redhat.com> (raw)
In-Reply-To: <41c08a5371957acac5310a2e608b2e42bd231558.camel@intel.com>

On 5/10/22 21:58, ying.huang@intel.com wrote:
> On Tue, 2022-05-10 at 11:05 -0700, Linus Torvalds wrote:
>> [ Adding locking people in case they have any input ]
>>
>> On Mon, May 9, 2022 at 11:23 PM ying.huang@intel.com
>> <ying.huang@intel.com> wrote:
>>>> Can you point me to the regression report? I would like to take a look,
>>>> thanks.
>>> https://lore.kernel.org/all/1425108604.10337.84.camel@linux.intel.com/
>> +
>> Hmm.
>>
>> That explanation looks believable, except that our qspinlocks
>> shouldn't be spinning on the lock itself, but spinning on the mcs node
>> it inserts into the lock.
> The referenced regression report is very old (in Feb 2015 for 3.16-
> 3.17).  The ticket spinlock was still used at that time.  I believe that
> things become much better after we used qspinlock.  We can test that.

Thank for the info. Qspinlock was merged into mainline since 4.2. So 
ticket spinlock was used on all v3.* kernels. I was wondering why 
qspinlock would have produced such a large performance regression with 
just one lock spinning head waiter. So this is not such a big issue 
after all.

Cheers,
Longman


  reply	other threads:[~2022-05-11  2:06 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-20  1:35 [mm/page_alloc] f26b3fa046: netperf.Throughput_Mbps -18.0% regression kernel test robot
2022-04-29 11:29 ` Aaron Lu
2022-04-29 13:39   ` Mel Gorman
2022-05-05  8:27     ` Aaron Lu
2022-05-05 11:09       ` Mel Gorman
2022-05-05 14:29         ` Aaron Lu
2022-05-06  8:40   ` ying.huang
2022-05-06 12:17     ` Aaron Lu
2022-05-07  0:54       ` ying.huang
2022-05-07  3:27         ` Aaron Lu
2022-05-07  7:11           ` ying.huang
2022-05-07  7:31             ` Aaron Lu
2022-05-07  7:44               ` ying.huang
2022-05-10  3:43                 ` Aaron Lu
2022-05-10  6:23                   ` ying.huang
2022-05-10 18:05                     ` Linus Torvalds
2022-05-10 18:47                       ` Waiman Long
2022-05-10 19:03                         ` Linus Torvalds
2022-05-10 19:25                           ` Linus Torvalds
2022-05-10 19:46                           ` Waiman Long
2022-05-10 19:27                       ` Peter Zijlstra
2022-05-11  1:58                       ` ying.huang
2022-05-11  2:06                         ` Waiman Long [this message]
2022-05-11 11:04                         ` Aaron Lu
2022-05-12  3:17                           ` ying.huang
2022-05-12 12:45                             ` Aaron Lu
2022-05-12 17:42                               ` Linus Torvalds
2022-05-12 18:06                                 ` Andrew Morton
2022-05-12 18:49                                   ` Linus Torvalds
2022-06-14  2:09                                     ` Feng Tang
2022-05-13  6:19                                 ` ying.huang
2022-05-11  3:40                     ` Aaron Lu
2022-05-11  7:32                       ` ying.huang
2022-05-11  7:53                         ` Aaron Lu
2022-06-01  2:19                           ` Aaron Lu

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=e3d60afb-b761-ef91-f73d-5fadc32050d5@redhat.com \
    --to=longman@redhat.com \
    --cc=aaron.lu@intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=brouer@redhat.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=feng.tang@intel.com \
    --cc=fengwei.yin@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lkp@intel.com \
    --cc=lkp@lists.01.org \
    --cc=mgorman@techsingularity.net \
    --cc=mhocko@kernel.org \
    --cc=oliver.sang@intel.com \
    --cc=peterz@infradead.org \
    --cc=torvalds@linux-foundation.org \
    --cc=vbabka@suse.cz \
    --cc=will@kernel.org \
    --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).