public inbox for cgroups@vger.kernel.org
 help / color / mirror / Atom feed
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Yosry Ahmed <yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Josef Bacik <josef-DigfWCa+lFGyeJad7bwFQA@public.gmane.org>,
	Jens Axboe <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>,
	Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
	Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Roman Gushchin
	<roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>,
	Muchun Song <muchun.song-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Vasily Averin
	<vasily.averin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	bpf-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [RFC PATCH 1/7] cgroup: rstat: only disable interrupts for the percpu lock
Date: Thu, 30 Mar 2023 15:51:35 -1000	[thread overview]
Message-ID: <ZCY8p/i6DR2tXPLP@slm.duckdns.org> (raw)
In-Reply-To: <98cb3ce-7ed9-3d17-9015-ef7193d6627-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

Hello, Hugh.

On Wed, Mar 29, 2023 at 01:38:48PM -0700, Hugh Dickins wrote:
> > So, in general, there's a trade off between local irq service latency and
> > inducing global lock contention when using unprotected locks. With more and
> > more CPUs, the balance keeps shifting. The balance still very much depends
> > on the specifics of a given lock but yeah I think it's something we need to
> > be a lot more careful about now.
> 
> And this looks a very plausible argument to me: I'll let it sink in.

Another somewhat relevant change is that flipping irq on/off used to be
relatively expensive on older x86 cpus. I forget all details about when and
how much but they should be a lot cheaper now. No idea about !x86 cpus tho.

> But I hadn't heard that the RT folks were clamouring for more irq disabling:
> perhaps they partition their machines with more care, and are not devotees
> of high CPU counts.

I think RT folks care a lot more about raw IRQ disables. These shouldn't
actually disable IRQs on RT kernels.

Thanks.

-- 
tejun

  parent reply	other threads:[~2023-03-31  1:51 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-23  4:00 [RFC PATCH 0/7] Make rstat flushing IRQ and sleep friendly Yosry Ahmed
     [not found] ` <20230323040037.2389095-1-yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2023-03-23  4:00   ` [RFC PATCH 1/7] cgroup: rstat: only disable interrupts for the percpu lock Yosry Ahmed
     [not found]     ` <20230323040037.2389095-2-yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2023-03-23  4:29       ` Shakeel Butt
     [not found]         ` <CALvZod7e7dMmkhKtXPAxmXjXQoTyeBf3Bht8HJC8AtWW93As3g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23  5:15           ` Yosry Ahmed
     [not found]             ` <CAJD7tkbziGh+6hnMysHkoNr_HGBKU+s1rSGj=gZLki0ALT-jLg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23  6:33               ` Shakeel Butt
2023-03-23 13:35                 ` Yosry Ahmed
     [not found]                   ` <CAJD7tkY6Wf2OWja+f-JeFM5DdMCyLzbXxZ8KF0MjcYOKri-vtA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23 15:40                     ` Shakeel Butt
2023-03-23 15:42                       ` Yosry Ahmed
2023-03-23 15:46                         ` Shakeel Butt
2023-03-23 16:09                           ` Shakeel Butt
     [not found]                             ` <CALvZod7-6F84POkNetA2XJB-24wms=5q_s495NEthO8b63rL4A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23 16:17                               ` Yosry Ahmed
     [not found]                                 ` <CAJD7tkbGCgk9VkGdec0=AdHErds4XQs1LzJMhqVryXdjY5PVAg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23 16:29                                   ` Shakeel Butt
     [not found]                                     ` <CALvZod7saq910u4JxnuY4C7EwiK5vgNF=-Bv+236RprUOQdkjw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23 16:36                                       ` Yosry Ahmed
     [not found]                                         ` <CAJD7tkb8oHoK5RW96tEXjY9iyJpMXfGAvnFw1rG-5Sr+Mpubdg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23 16:45                                           ` Shakeel Butt
     [not found]                                             ` <CALvZod5USCtNtnPuYRbRv_psBCNytQWWQ592TFsJLfrLpyLJmw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23 16:51                                               ` Yosry Ahmed
2023-03-23 19:09                                                 ` Shakeel Butt
2023-03-23 17:33                                 ` Johannes Weiner
     [not found]                                   ` <20230323173343.GF739026-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2023-03-23 18:09                                     ` Yosry Ahmed
2023-03-23 18:19                                       ` Johannes Weiner
2023-03-24  1:39       ` Tejun Heo
2023-03-24  7:22         ` Yosry Ahmed
2023-03-24 14:12           ` Waiman Long
2023-03-24 22:50             ` Yosry Ahmed
     [not found]           ` <CAJD7tkYNZeEytm_Px9_73Y-AYJfHAxaoTmmnO71HW5hd1B5tPg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-25  1:54             ` Tejun Heo
2023-03-25  2:17               ` Yosry Ahmed
     [not found]                 ` <CAJD7tkYhyMkD8SFf8b8L1W9QUrLOdw-HJ2NUbENjw5dgFnH3Aw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-25  4:30                   ` Shakeel Butt
2023-03-25  4:37                     ` Yosry Ahmed
2023-03-25  4:46                       ` Shakeel Butt
2023-03-27 23:23                         ` Yosry Ahmed
2023-03-29 18:53                           ` Tejun Heo
2023-03-29 19:22                             ` Hugh Dickins
     [not found]                               ` <f9b6410-ee17-635f-a35d-559fa0191dc3-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2023-03-29 20:00                                 ` Tejun Heo
     [not found]                                   ` <ZCSY8l/jVwszF6iA-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2023-03-29 20:38                                     ` Hugh Dickins
     [not found]                                       ` <98cb3ce-7ed9-3d17-9015-ef7193d6627-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2023-03-30  4:26                                         ` Yosry Ahmed
2023-03-31  1:51                                         ` Tejun Heo [this message]
2023-03-23  4:00   ` [RFC PATCH 6/7] workingset: memcg: sleep when flushing stats in workingset_refault() Yosry Ahmed
2023-03-23 15:50     ` Johannes Weiner
2023-03-23 16:02       ` Yosry Ahmed
2023-03-23 16:00     ` Johannes Weiner
     [not found]       ` <20230323160030.GD739026-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2023-03-23 16:02         ` Yosry Ahmed
2023-03-23  4:10   ` [RFC PATCH 0/7] Make rstat flushing IRQ and sleep friendly Shakeel Butt
2023-03-23  5:07     ` Yosry Ahmed
2023-03-23  4:00 ` [RFC PATCH 2/7] memcg: do not disable interrupts when holding stats_flush_lock Yosry Ahmed
2023-03-23  4:32   ` Shakeel Butt
     [not found]     ` <CALvZod5MnM8UJ0pj44QYb4sVwgFZ1B2KpSL6oqBQbJU3wH6eNA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23  5:16       ` Yosry Ahmed
2023-03-23  4:00 ` [RFC PATCH 3/7] cgroup: rstat: remove cgroup_rstat_flush_irqsafe() Yosry Ahmed
2023-03-23 15:43   ` Johannes Weiner
2023-03-23 15:45     ` Yosry Ahmed
2023-03-23  4:00 ` [RFC PATCH 4/7] memcg: sleep during flushing stats in safe contexts Yosry Ahmed
2023-03-23 15:56   ` Johannes Weiner
2023-03-23 16:01     ` Yosry Ahmed
     [not found]       ` <CAJD7tkZ7Dz9myftc9bg7jhiaOYcn7qJ+V4sxZ_2kfnb+k=zhJQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2023-03-23 17:27         ` Johannes Weiner
     [not found]           ` <20230323172732.GE739026-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2023-03-23 18:07             ` Yosry Ahmed
2023-03-23 19:35               ` Shakeel Butt
2023-03-23  4:00 ` [RFC PATCH 5/7] vmscan: memcg: sleep when flushing stats during reclaim Yosry Ahmed
2023-03-23  4:00 ` [RFC PATCH 7/7] memcg: do not modify rstat tree for zero updates Yosry Ahmed

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=ZCY8p/i6DR2tXPLP@slm.duckdns.org \
    --to=tj-dgejt+ai2ygdnm+yrofe0a@public.gmane.org \
    --cc=akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
    --cc=axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org \
    --cc=bpf-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org \
    --cc=hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org \
    --cc=josef-DigfWCa+lFGyeJad7bwFQA@public.gmane.org \
    --cc=linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org \
    --cc=lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org \
    --cc=mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
    --cc=muchun.song-fxUVXftIFDnyG1zEObXtfA@public.gmane.org \
    --cc=roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org \
    --cc=shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org \
    --cc=vasily.averin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org \
    --cc=yosryahmed-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org \
    /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