From: Prarit Bhargava <prarit@redhat.com>
To: rui wang <ruiv.wang@gmail.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, "Chen,
Gong" <gong.chen@intel.com>, "Yu, Fenghua" <fenghua.yu@intel.com>
Subject: Re: [PATCH] x86: Add check for number of available vectors before CPU down
Date: Wed, 18 Dec 2013 14:28:26 -0500 [thread overview]
Message-ID: <52B1F75A.6090403@redhat.com> (raw)
In-Reply-To: <CANVTcTZo8pN8y7UiSFyGNLWNwRm8nwQyzCFdQJy50z95vV15oQ@mail.gmail.com>
On 12/03/2013 09:48 PM, rui wang wrote:
> On 11/20/13, Prarit Bhargava <prarit@redhat.com> wrote:
> Have you considered the case when an IRQ is destined to more than one CPU? e.g.:
>
> bash# cat /proc/irq/89/smp_affinity_list
> 30,62
> bash#
>
> In this case offlining CPU30 does not seem to require an empty vector
> slot. It seems that we only need to change the affinity mask of irq89.
> Your check_vectors() assumed that each irq on the offlining cpu
> requires a new vector slot.
>
Rui,
The smp_affinity_list only indicates a preferred destination of the IRQ, not the
*actual* location of the CPU. So the IRQ is on one of cpu 30 or 62 but not both
simultaneously.
If the case is that 62 is being brought down, then the smp_affinity mask will be
updated to reflect only cpu 30 (and vice versa).
P.
next prev parent reply other threads:[~2013-12-18 19:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 16:24 [PATCH] x86: Add check for number of available vectors before CPU down Prarit Bhargava
2013-12-03 23:42 ` Yu, Fenghua
2013-12-04 15:15 ` Prarit Bhargava
2013-12-04 2:48 ` rui wang
2013-12-18 19:28 ` Prarit Bhargava [this message]
2013-12-19 7:19 ` rui wang
2013-12-19 13:33 ` Prarit Bhargava
2013-12-19 19:03 ` Prarit Bhargava
-- strict thread matches above, loose matches on Subject: below --
2013-12-02 13:18 Prarit Bhargava
2013-11-11 16:00 Prarit Bhargava
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