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From: Andrei Vagin <avagin@virtuozzo.com>
To: Keith Busch <keith.busch@intel.com>
Cc: <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Xiaolong Ye <xiaolong.ye@intel.com>
Subject: Re: irq/affinity: Fix extra vecs calculation
Date: Wed, 19 Apr 2017 09:20:27 -0700	[thread overview]
Message-ID: <20170419162027.GA7428@outlook.office365.com> (raw)
In-Reply-To: <1492104492-19943-1-git-send-email-keith.busch@intel.com>

Hi,

Something is wrong with this patch. We run CRIU tests for upstream kernels.
And we found that a kernel with this patch can't be booted.

https://travis-ci.org/avagin/linux/builds/223557750

We don't have access to console logs and I can't reproduce this issue on
my nodes. I tired to revert this patch and everything works as expected.

https://travis-ci.org/avagin/linux/builds/223594172

Here is another report about this patch
https://lkml.org/lkml/2017/4/16/344

Thanks,
Andrei

On Thu, Apr 13, 2017 at 01:28:12PM -0400, Keith Busch wrote:
> This fixes a math error calculating the extra_vecs. The error assumed
> only 1 cpu per vector, but the value needs to account for the actual
> number of cpus per vector in order to get the correct remainder for
> extra CPU assignment.
> 
> Fixes: 7bf8222b9bd0 ("irq/affinity: Fix CPU spread for unbalanced nodes")
> Reported-by: Xiaolong Ye <xiaolong.ye@intel.com>
> Signed-off-by: Keith Busch <keith.busch@intel.com>
> ---
>  kernel/irq/affinity.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
> index dc52911..d052947 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -108,7 +108,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
>  		vecs_to_assign = min(vecs_per_node, ncpus);
>  
>  		/* Account for rounding errors */
> -		extra_vecs = ncpus - vecs_to_assign;
> +		extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
>  
>  		for (v = 0; curvec < last_affv && v < vecs_to_assign;
>  		     curvec++, v++) {

  parent reply	other threads:[~2017-04-19 16:20 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-13 17:28 [PATCH] " Keith Busch
2017-04-13 21:46 ` [tip:irq/urgent] " tip-bot for Keith Busch
2017-04-19 16:20 ` Andrei Vagin [this message]
2017-04-19 17:03   ` Keith Busch
2017-04-19 19:11     ` Andrei Vagin
2017-04-19 19:53     ` Andrei Vagin
2017-04-19 21:53       ` Keith Busch
2017-04-19 22:32         ` Andrei Vagin
2017-04-19 22:45           ` Keith Busch

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