linux-kernel - Re: [PATCH 4/4][RFC v2] x86/apic: Spread the vectors by choosing the idlest CPU

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170907025728.GB18130@localhost.localdomain>
Date:   Thu, 7 Sep 2017 10:57:29 +0800
From:   Yu Chen <yu.c.chen@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Christoph Hellwig <hch@....de>,
        Thomas Gleixner <tglx@...utronix.de>, X86 ML <x86@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Rui Zhang <rui.zhang@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 4/4][RFC v2] x86/apic: Spread the vectors by choosing the
 idlest CPU

On Wed, Sep 06, 2017 at 10:46:17AM -0700, Dan Williams wrote:
> On Tue, Sep 5, 2017 at 11:15 PM, Christoph Hellwig <hch@....de> wrote:
> > On Wed, Sep 06, 2017 at 12:13:38PM +0800, Yu Chen wrote:
> >> I agree, the driver could be rewritten, but it might take some time, so
> >> meanwhile I'm looking at also other possible optimization.
> >
> > Which driver are we talking about anyway?  Let's start looking at it
> > and fix the issue there.
> 
> As far as I understand, it's already fixed there:
> 
> commit 7c9ae7f053e9e896c24fd23595ba369a5fe322e1
> Author: Carolyn Wyborny <carolyn.wyborny@...el.com>
> Date:   Tue Jun 20 15:16:53 2017 -0700
> 
>     i40e: Fix for trace found with S4 state
> 
>     This patch fixes a problem found in systems when entering
>     S4 state.  This patch fixes the problem by ensuring that
>     the misc vector's IRQ is disabled as well.  Without this
>     patch a stack trace can be seen upon entering S4 state.
> 
> However this seems like something that should be handled generically
> in the irq-core especially since commit c5cb83bb337c
> "genirq/cpuhotplug: Handle managed IRQs on CPU hotplug" was headed in
> that direction. It's otherwise non-obvious when a driver needs to
> release and re-acquire interrupts or be reworked to use managed
> interrupts.
Yes, thanks for the explaination! I did not notice this patch has
been merged already.
I'm using the normal CPU hotplug to reproduce the issue:
#!/bin/bash

n=1

while [ $n -le 31 ]
do
	echo 0 > /sys/devices/system/cpu/cpu${n}/online
	n=$(( n+1 ))
done

Thanks,
	Yu