From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <song@kernel.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2] watchdog: Prefer use "ref-cycles" for NMI watchdog
Date: Wed, 17 May 2023 09:31:19 +0200 [thread overview]
Message-ID: <20230517073119.GA2665450@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230516235817.2323062-1-song@kernel.org>
On Tue, May 16, 2023 at 04:58:17PM -0700, Song Liu wrote:
> NMI watchdog permanently consumes one hardware counters per CPU on the
> system. For systems that use many hardware counters, this causes more
> aggressive time multiplexing of perf events.
>
> OTOH, some CPUs (mostly Intel) support "ref-cycles" event, which is rarely
> used. Try use "ref-cycles" for the watchdog, so that one more hardware
> counter is available to the user. If the CPU doesn't support "ref-cycles",
> fall back to "cycles".
>
> The downside of this change is that users of "ref-cycles" need to disable
> nmi_watchdog.
I still utterly hate how you hardcode ref-cycles
next prev parent reply other threads:[~2023-05-17 7:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-16 23:58 [PATCH v2] watchdog: Prefer use "ref-cycles" for NMI watchdog Song Liu
2023-05-17 1:23 ` Li, Xin3
2023-05-17 4:38 ` Song Liu
2023-05-17 7:31 ` Peter Zijlstra [this message]
2023-05-17 17:51 ` Song Liu
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