Date: Wed, 6 Jun 2012 21:41:02 +0200
From: Alexander Gordeev <agordeev@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
        Suresh Siddha <suresh.b.siddha@intel.com>,
        Yinghai Lu <yinghai@kernel.org>
Subject: Re: [PATCH 5/8] x86: apic: Try to spread IRQ vectors to different
 priority levels
Message-ID: <20120606194101.GB4777@dhcp-26-207.brq.redhat.com>
References: <20120605112408.GA11466@dhcp-26-207.brq.redhat.com>
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On Wed, Jun 06, 2012 at 12:16:08PM -0700, Eric W. Biederman wrote:
> Alexander Gordeev <agordeev@redhat.com> writes:
> 
> > When assigning a new vector it is primarially done by adding 8 to the
> > previously given out vector number. Hence, two consequently allocated
> > vector numbers would likely fall into the same priority level. Try to
> > spread vector numbers to different priority levels better by changing
> > the step from 8 to 16.
> 
> A weird goal.  Given that linux ignores all priority levels internally
> we would be better incrementing by 1.  The practical problem is that
> some older hardware would fail if you had more than two devices per
> priority level.

Yes, the patch is aimed at those older hardware. For a newer hardware it will
not bring any change.

But also to stop asking myself: why 8, not 1 or 16? :)

> Eric

-- 
Regards,
Alexander Gordeev
agordeev@redhat.com
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