linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andi Kleen <ak@linux.intel.com>
To: Feng Tang <feng.tang@intel.com>
Cc: Michal Koutn?? <mkoutny@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	andi.kleen@intel.com, kernel test robot <oliver.sang@intel.com>,
	Roman Gushchin <guro@fb.com>, Michal Hocko <mhocko@suse.com>,
	Shakeel Butt <shakeelb@google.com>,
	Balbir Singh <bsingharora@gmail.com>, Tejun Heo <tj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	lkp@lists.01.org, kernel test robot <lkp@intel.com>,
	"Huang, Ying" <ying.huang@intel.com>,
	Zhengjun Xing <zhengjun.xing@linux.intel.com>
Subject: Re: [mm] 2d146aa3aa: vm-scalability.throughput -36.4% regression
Date: Wed, 1 Sep 2021 19:23:24 -0700	[thread overview]
Message-ID: <e8d087a4-a286-3561-66ef-1e9cfb38605f@linux.intel.com> (raw)
In-Reply-To: <20210902013558.GA97410@shbuild999.sh.intel.com>


On 9/1/2021 6:35 PM, Feng Tang wrote:
> On Wed, Sep 01, 2021 at 08:12:24AM -0700, Andi Kleen wrote:
>> Feng Tang <feng.tang@intel.com> writes:
>>> Yes, the tests I did is no matter where the 128B padding is added, the
>>> performance can be restored and even improved.
>> I wonder if we can find some cold, rarely accessed, data to put into the
>> padding to not waste it. Perhaps some name strings? Or the destroy
>> support, which doesn't sound like its commonly used.
> Yes, I tried to move 'destroy_work', 'destroy_rwork' and 'parent' over
> before the 'refcnt' together with some padding, it restored the performance
> to about 10~15% regression. (debug patch pasted below)
>
> But I'm not sure if we should use it, before we can fully explain the
> regression.

Narrowing it down to a single prefetcher seems good enough to me. The 
behavior of the prefetchers is fairly complicated and hard to predict, 
so I doubt you'll ever get a 100% step by step explanation.


-Andi



  reply	other threads:[~2021-09-02  2:23 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-11  3:17 [mm] 2d146aa3aa: vm-scalability.throughput -36.4% regression kernel test robot
2021-08-11  5:59 ` Linus Torvalds
2021-08-11 20:12   ` Johannes Weiner
2021-08-12  3:19   ` Feng Tang
2021-08-16  3:28     ` Feng Tang
2021-08-16 21:41       ` Johannes Weiner
2021-08-17  2:45         ` Feng Tang
2021-08-17 16:47           ` Michal Koutný
2021-08-17 17:10             ` Shakeel Butt
2021-08-18  2:30             ` Feng Tang
2021-08-30 14:51               ` Michal Koutný
2021-08-31  6:30                 ` Feng Tang
2021-08-31  9:23                   ` Michal Koutný
2021-09-01  4:50                     ` Feng Tang
2021-09-01 15:12                       ` Andi Kleen
2021-09-02  1:35                         ` Feng Tang
2021-09-02  2:23                           ` Andi Kleen [this message]
2021-09-02  3:46                             ` Feng Tang
2021-09-02 10:53                               ` Michal Koutný
2021-09-02 13:39                                 ` Feng Tang

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=e8d087a4-a286-3561-66ef-1e9cfb38605f@linux.intel.com \
    --to=ak@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=andi.kleen@intel.com \
    --cc=bsingharora@gmail.com \
    --cc=feng.tang@intel.com \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lkp@intel.com \
    --cc=lkp@lists.01.org \
    --cc=mhocko@suse.com \
    --cc=mkoutny@suse.com \
    --cc=oliver.sang@intel.com \
    --cc=shakeelb@google.com \
    --cc=tj@kernel.org \
    --cc=torvalds@linux-foundation.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).