From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-kernel@vger.kernel.org,
Frederic Weisbecker <frederic@kernel.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH] kernel/isolation: Asset that a housekeeping CPU comes up at boot time
Date: Mon, 17 Jun 2019 17:59:31 +0200 [thread overview]
Message-ID: <20190617155931.GK3436@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1560151344.y4aukciain.astroid@bobo.none>
On Mon, Jun 10, 2019 at 05:24:32PM +1000, Nicholas Piggin wrote:
> Nicholas Piggin's on June 1, 2019 9:39 pm:
> > With the change to allow the boot CPU0 to be isolated, it is possible
> > to specify command line options that result in no housekeeping CPU
> > online at boot.
> >
> > An 8 CPU system booted with "nohz_full=0-6 maxcpus=4", for example.
> >
> > It is not easily possible at housekeeping init time to know all the
> > various SMP options that will result in an invalid configuration, so
> > this patch adds a sanity check after SMP init, to ensure that a
> > housekeeping CPU has been onlined.
> >
> > The panic is undesirable, but it's better than the alternative of an
> > obscure non deterministic failure. The panic will reliably happen
> > when advanced parameters are used incorrectly.
>
> Ping on this one? This should resolve Frederic's remaining objection
> to the series (at least until he solves it more generally).
>
> As the series has already been merged, should we get this upstream
> before release?
I was hoping for feedback from Frederic, lacking that, I've queued it
now.
next prev parent reply other threads:[~2019-06-17 15:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-01 11:39 [PATCH] kernel/isolation: Asset that a housekeeping CPU comes up at boot time Nicholas Piggin
2019-06-10 7:24 ` Nicholas Piggin
2019-06-17 15:59 ` Peter Zijlstra [this message]
2019-06-17 19:05 ` Frederic Weisbecker
2019-06-19 2:40 ` Nicholas Piggin
2019-06-24 10:57 ` Qais Yousef
2019-06-25 0:05 ` Nicholas Piggin
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