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From: Marcelo Tosatti <mtosatti@redhat.com>
To: Hillf Danton <hdanton@sina.com>
Cc: atomlin@atomlin.com, frederic@kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v13 3/6] mm/vmstat: manage per-CPU stats from CPU context when NOHZ full
Date: Tue, 10 Jan 2023 08:50:28 -0300	[thread overview]
Message-ID: <Y71RBDZqV1Ad+GVr@tpad> (raw)
In-Reply-To: <20230110024356.336-1-hdanton@sina.com>

On Tue, Jan 10, 2023 at 10:43:56AM +0800, Hillf Danton wrote:
> On 9 Jan 2023 11:12:49 -0300 Marcelo Tosatti <mtosatti@redhat.com>
> > 
> > Yes, but if you do not return to userspace, then the per-CPU vm
> > statistics can be dirty indefinitely.
> 
> Could you specify the reasons for failing to return to userspace,
> given it is undesired intereference for the shepherd to queue work
> on the isolated CPUs.

Any system call that takes longer than the threshold to sync vmstats.

Or a long running kernel thread, for example:

https://stackoverflow.com/questions/65111483/long-running-kthread-and-synchronize-net



  reply	other threads:[~2023-01-10 14:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-05 12:52 [PATCH v13 0/6] Ensure quiet_vmstat() is called when returning to userpace and when idle tick is stopped Marcelo Tosatti
2023-01-05 12:52 ` [PATCH v13 1/6] mm/vmstat: Add CPU-specific variable to track a vmstat discrepancy Marcelo Tosatti
2023-01-10 11:58   ` Christoph Lameter
2023-01-10 12:12     ` Frederic Weisbecker
2023-01-05 12:52 ` [PATCH v13 2/6] mm/vmstat: Use vmstat_dirty to track CPU-specific vmstat discrepancies Marcelo Tosatti
2023-01-10 12:06   ` Christoph Lameter
2023-01-10 12:18     ` Frederic Weisbecker
2023-01-10 13:39       ` Christoph Lameter
2023-01-10 20:09         ` Marcelo Tosatti
2023-01-11  8:42           ` Christoph Lameter
2023-01-11 17:07             ` Marcelo Tosatti
2023-01-16  9:51               ` Christoph Lameter
2023-01-16 16:11                 ` Marcelo Tosatti
2023-01-17 12:52                   ` Christoph Lameter
2023-01-05 12:52 ` [PATCH v13 3/6] mm/vmstat: manage per-CPU stats from CPU context when NOHZ full Marcelo Tosatti
2023-01-05 12:52 ` [PATCH v13 4/6] tick/nohz_full: Ensure quiet_vmstat() is called on exit to user-mode when the idle tick is stopped Marcelo Tosatti
2023-01-05 12:52 ` [PATCH v13 5/6] tick/sched: Ensure quiet_vmstat() is called when the idle tick was stopped too Marcelo Tosatti
2023-01-05 12:52 ` [PATCH v13 6/6] mm/vmstat: avoid queueing work item if cpu stats are clean Marcelo Tosatti
     [not found] ` <20230106001244.4463-1-hdanton@sina.com>
2023-01-06 12:51   ` [PATCH v13 3/6] mm/vmstat: manage per-CPU stats from CPU context when NOHZ full Marcelo Tosatti
2023-01-06 15:01     ` Hillf Danton
2023-01-06 18:16       ` Marcelo Tosatti
2023-01-07  0:15         ` Hillf Danton
2023-01-09 14:12           ` Marcelo Tosatti
2023-01-10  2:43             ` Hillf Danton
2023-01-10 11:50               ` Marcelo Tosatti [this message]
2023-01-10 15:19                 ` Hillf Danton
2023-01-10 16:12                   ` Frederic Weisbecker
2023-01-10 23:58                     ` Hillf Danton
2023-01-11  0:09                       ` Frederic Weisbecker

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