From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Zachary Amsden <zach@vmware.com>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: Strange IO behaviour on wakeup from sleep
Date: Thu, 28 Oct 2004 08:40:31 +1000 [thread overview]
Message-ID: <1098916831.9478.27.camel@gaston> (raw)
In-Reply-To: <417FAE3F.20908@vmware.com>
On Wed, 2004-10-27 at 07:18 -0700, Zachary Amsden wrote:
> I would tend to be very suspicious of DMA not being restored correctly
> because on some systems, prior to or during suspend, DMA may be shutdown
> to conserve power. There are changes afloat that touch suspend/resume,
> and there have been historical problems with DMA not being restored
> properly after wakeup on some laptops.
DMA is restored, and the resulting is way slower than what PIO would
explain anyway. I get less than 100Kb/sec !
(I wrote the IDE suspend/resume code and the driver for this chipset, so
I'm fairly sure that side is ok, it didn't change for a while, but I'll
double check in case Bart latest updates broke something).
> Although this may be another shot in the dark, it might rule out the DMA
> problem: try cat /proc/ide/yourchipset before and after suspend and
> note any changes. Failing that, use hdparm to turn off DMA before
> suspend and see if the performance suffers to the same degree as after
> wakeup.
Tried all of that.
Ben.
next prev parent reply other threads:[~2004-10-27 22:49 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-27 14:18 Strange IO behaviour on wakeup from sleep Zachary Amsden
2004-10-27 22:40 ` Benjamin Herrenschmidt [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-10-27 2:56 Benjamin Herrenschmidt
2004-10-27 6:24 ` Jens Axboe
2004-10-27 11:20 ` Tim Schmielau
2004-10-27 12:06 ` Benjamin Herrenschmidt
2004-10-27 12:13 ` Tim Schmielau
2004-10-27 13:01 ` Nigel Cunningham
2004-10-27 13:08 ` Benjamin Herrenschmidt
2004-10-27 13:20 ` Nigel Cunningham
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