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From: Peter Xu <peterx@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Christoph Lameter <cl@linux.com>,
	Aaron Tomlin <atomlin@atomlin.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2 09/11] mm/vmstat: use cmpxchg loop in cpu_vm_stats_fold
Date: Thu, 2 Mar 2023 16:19:50 -0500	[thread overview]
Message-ID: <ZAES9hPHJGGgCBfc@x1n> (raw)
In-Reply-To: <ZACqvbnYAKumb+8O@tpad>

On Thu, Mar 02, 2023 at 10:55:09AM -0300, Marcelo Tosatti wrote:
> >   (2) If someone can modify the dead cpu's vm_stat_diff,
> 
> The only context that can modify the cpu's vm_stat_diff are:
> 
> 1) The CPU itself (increases the counter).
> 2) cpu_vm_stats_fold (from vmstat_shepherd kernel thread), from 
> x -> 0 only.

I think I didn't continue reading so I didn't see cpu_vm_stats_fold() will
be reused when commenting, sorry.

Now with a reworked (and SMP-safe) cpu_vm_stats_fold() and vmstats, I'm
wondering the possibility of merging it with refresh_cpu_vm_stats() since
they really look similar.

IIUC the new refresh_cpu_vm_stats() logically doesn't need the small
preempt disabled sections, not anymore, if with a cpu_id passed over to
cpu_vm_stats_fold(), which seems to be even a good side effect. But not
sure I missed something.

-- 
Peter Xu


  reply	other threads:[~2023-03-02 22:23 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-09 15:01 [PATCH v2 00/11] fold per-CPU vmstats remotely Marcelo Tosatti
2023-02-09 15:01 ` [PATCH v2 01/11] mm/vmstat: remove remote node draining Marcelo Tosatti
2023-02-28 15:53   ` David Hildenbrand
2023-02-28 19:36     ` Marcelo Tosatti
2023-03-02 10:10       ` David Hildenbrand
2023-03-21 15:20         ` Mel Gorman
2023-03-21 17:31           ` Marcelo Tosatti
2023-03-02 17:21   ` Peter Xu
2023-03-02 17:27     ` Peter Xu
2023-03-02 19:17       ` Marcelo Tosatti
2023-03-02 18:56     ` Marcelo Tosatti
2023-02-09 15:01 ` [PATCH v2 02/11] this_cpu_cmpxchg: ARM64: switch this_cpu_cmpxchg to locked, add _local function Marcelo Tosatti
2023-03-02 10:42   ` David Hildenbrand
2023-03-02 10:51     ` David Hildenbrand
2023-03-02 14:32     ` Marcelo Tosatti
2023-03-02 20:53   ` Peter Xu
2023-03-02 21:04     ` Marcelo Tosatti
2023-03-02 21:25       ` Peter Xu
2023-03-03 15:39         ` Marcelo Tosatti
2023-03-03 15:47     ` Marcelo Tosatti
2023-03-15 23:56   ` Christoph Lameter
2023-03-16 10:54     ` Marcelo Tosatti
2023-02-09 15:01 ` [PATCH v2 03/11] this_cpu_cmpxchg: loongarch: " Marcelo Tosatti
2023-02-09 15:01 ` [PATCH v2 04/11] this_cpu_cmpxchg: S390: " Marcelo Tosatti
2023-02-09 15:01 ` [PATCH v2 05/11] this_cpu_cmpxchg: x86: " Marcelo Tosatti
2023-02-09 15:01 ` [PATCH v2 06/11] this_cpu_cmpxchg: asm-generic: " Marcelo Tosatti
2023-02-09 15:01 ` [PATCH v2 07/11] convert this_cpu_cmpxchg users to this_cpu_cmpxchg_local Marcelo Tosatti
2023-03-02 20:54   ` Peter Xu
2023-02-09 15:01 ` [PATCH v2 08/11] mm/vmstat: switch counter modification to cmpxchg Marcelo Tosatti
2023-03-02 10:47   ` David Hildenbrand
2023-03-02 14:47     ` Marcelo Tosatti
2023-03-02 16:20       ` Peter Xu
2023-03-02 19:11         ` Marcelo Tosatti
2023-03-02 20:06           ` Peter Xu
2023-02-09 15:01 ` [PATCH v2 09/11] mm/vmstat: use cmpxchg loop in cpu_vm_stats_fold Marcelo Tosatti
2023-03-01 22:57   ` Peter Xu
2023-03-02 13:55     ` Marcelo Tosatti
2023-03-02 21:19       ` Peter Xu [this message]
2023-03-03 15:17         ` Marcelo Tosatti
2023-02-09 15:02 ` [PATCH v2 10/11] mm/vmstat: switch vmstat shepherd to flush per-CPU counters remotely Marcelo Tosatti
2023-03-02 21:01   ` Peter Xu
2023-03-02 21:16     ` Marcelo Tosatti
2023-03-02 21:30       ` Peter Xu
2023-02-09 15:02 ` [PATCH v2 11/11] mm/vmstat: refresh stats remotely instead of via work item Marcelo Tosatti
2023-02-23 14:54 ` [PATCH v2 00/11] fold per-CPU vmstats remotely Marcelo Tosatti
2023-02-24  2:34   ` Hillf Danton
2023-02-27 19:41     ` Marcelo Tosatti

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