From: Stephen Hemminger <shemminger@vyatta.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: jbarnes@virtuousgeek.org, bhutchings@solarflare.com,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] PCI: vpd handle longer delays in access
Date: Mon, 8 Sep 2008 14:08:24 -0700 [thread overview]
Message-ID: <20080908140824.5ab3c7ca@extreme> (raw)
In-Reply-To: <20080908134025.9ac23a73.akpm@linux-foundation.org>
On Mon, 8 Sep 2008 13:40:25 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:
> On Thu, 04 Sep 2008 13:56:37 -0700
> Stephen Hemminger <shemminger@vyatta.com> wrote:
>
> > Accessing the VPD area can take a long time. The existing
> > VPD access code fails consistently on my hardware. There are comments
> > in the SysKonnect vendor driver that it can take up to 13ms per word.
> >
> > Change the access routines to:
> > * use a mutex rather than spinning with IRQ's disabled and lock held
> > * have a longer timeout
> > * call schedule while spinning to provide some responsivness
>
> It doesn't call schedule() - it calls yield().
>
> yield() is pretty notoriously badly behaved in the presence of lots of
> runnable tasks and there's been a general move to eradicate its
> in-kernel callsites.
>
> An alternative would be nice.
What is a good way to say "i am polling for a while"?
next prev parent reply other threads:[~2008-09-08 21:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-04 20:56 [PATCH 0/3] PCI VPD changes Stephen Hemminger
2008-09-04 20:56 ` [PATCH 1/3] PCI: vpd handle longer delays in access Stephen Hemminger
2008-09-05 9:11 ` Peter Zijlstra
2008-09-05 12:40 ` Matthew Wilcox
2008-09-08 20:40 ` Andrew Morton
2008-09-08 21:08 ` Stephen Hemminger [this message]
2008-09-08 21:26 ` Arjan van de Ven
2008-09-09 16:55 ` Stephen Hemminger
2008-09-09 17:01 ` Arjan van de Ven
2008-09-04 20:56 ` [PATCH 2/3] PCI: revise VPD access interface Stephen Hemminger
2008-09-05 11:02 ` Ben Hutchings
2008-09-08 20:46 ` Andrew Morton
2008-09-04 20:56 ` [PATCH 3/3] PCI: add interface to set visible size of VPD Stephen Hemminger
2008-09-05 11:07 ` Ben Hutchings
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