From: Christoph Lameter <cl@gentwo.de>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: 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 3/5] mm/vmstat: use cmpxchg loop in cpu_vm_stats_fold
Date: Mon, 6 Feb 2023 10:42:46 +0100 (CET) [thread overview]
Message-ID: <47a289f0-ae96-e0e6-c579-70ec61fff384@gentwo.de> (raw)
In-Reply-To: <Y91X3hA5i7FQJwEo@tpad>
On Fri, 3 Feb 2023, Marcelo Tosatti wrote:
> > Isnt there some lock/serializtion to stall the kernel until you are done?
>
> Not that i know of. Anyway, an additional datapoint is:
>
> "Software defined PLC"
> (https://www.redhat.com/en/blog/software-defined-programmable-logic-controller-introduction),
> applications
> can perform system calls in their time sensitive loop.
>
> One example of an opensource software is OpenPLC.
>
> One would like to avoid interruptions for those cases as well.
Well allowing sytem calls during "time sensitiveness" implies
it is not that sensitive to vmstat updates which have a smaller impact
than system calls.
Unless we are talking about virtual system calls like gettimeofday or
clock_gettime. These do not enter the kernel if configured correctly.
next prev parent reply other threads:[~2023-02-06 9:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-01 19:50 [PATCH 0/5] fold per-CPU vmstats remotely Marcelo Tosatti
2023-02-01 19:50 ` [PATCH 1/5] mm/vmstat: remove remote node draining Marcelo Tosatti
2023-02-01 19:50 ` [PATCH 2/5] mm/vmstat: switch counter modification to cmpxchg Marcelo Tosatti
2023-02-01 19:50 ` [PATCH 3/5] mm/vmstat: use cmpxchg loop in cpu_vm_stats_fold Marcelo Tosatti
2023-02-02 14:38 ` Christoph Lameter
2023-02-02 15:54 ` Marcelo Tosatti
2023-02-03 9:34 ` Christoph Lameter
2023-02-03 18:52 ` Marcelo Tosatti
2023-02-06 9:42 ` Christoph Lameter [this message]
2023-02-06 19:10 ` Marcelo Tosatti
2023-02-06 19:19 ` Matthew Wilcox
2023-02-01 19:50 ` [PATCH 4/5] mm/vmstat: switch vmstat shepherd to flush per-CPU counters remotely Marcelo Tosatti
2023-02-01 19:50 ` [PATCH 5/5] mm/vmstat: refresh stats remotely instead of via work item Marcelo Tosatti
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