From: Dave Hansen <firstname.lastname@example.org> To: Rik van Riel <email@example.com>, firstname.lastname@example.org Cc: Dave Hansen <email@example.com>, Andy Lutomirski <firstname.lastname@example.org>, email@example.com, Peter Zijlstra <firstname.lastname@example.org>, Ingo Molnar <email@example.com>, Borislav Petkov <firstname.lastname@example.org>, email@example.com Subject: Re: [PATCH] x86,mm: print likely CPU at segfault time Date: Mon, 19 Jul 2021 12:20:24 -0700 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> On 7/19/21 12:00 PM, Rik van Riel wrote: > In a large enough fleet of computers, it is common to have a few bad > CPUs. Those can often be identified by seeing that some commonly run > kernel code (that runs fine everywhere else) keeps crashing on the > same CPU core on a particular bad system. I've encountered a few of these kinds of things over the years. This is *definitely* useful. What you've proposed here is surely the simplest thing we could print and probably also offers the best bang for our buck. The only other thing I thought of is that it might be nice to print out the core id instead of the CPU id. If there are hardware issues with a CPU, they're likely to affect both threads. Seeing to different "CPUs" in an SMT environment might tempt some folks to think it's not a core-level hardware issue. If it's as trivial as: printk(KERN_CONT " on cpu/core %d/%d", raw_smp_processor_id(), topology_core_id(raw_smp_processor_id())); it would be handy. But, it's also not hard to look at 10 segfaults, see that they happened only on 2 CPUs and realize that hyperthreading is enabled. Either way, this patch moves things in the right direction, so: Acked-by: Dave Hansen <firstname.lastname@example.org>
next prev parent reply other threads:[~2021-07-19 19:59 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-19 19:00 Rik van Riel 2021-07-19 19:20 ` Dave Hansen [this message] 2021-07-19 19:34 ` Rik van Riel 2021-07-21 20:38 ` Thomas Gleixner 2021-07-21 20:36 ` Thomas Gleixner 2021-07-24 1:38 ` Rik van Riel
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