From: Arjan van de Ven <arjan@linux.intel.com>
To: Tejun Heo <tj@kernel.org>
Cc: Jeff Garzik <jeff@garzik.org>,
t.artem@mailcity.com,
"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>
Subject: Re: ahci: CAP_SSS and parallel scan
Date: Thu, 06 May 2010 02:30:55 -0700 [thread overview]
Message-ID: <4BE28C4F.9000903@linux.intel.com> (raw)
In-Reply-To: <4BE27C49.5090809@kernel.org>
On 5/6/2010 1:22, Tejun Heo wrote:
> Hello,
>
> Artem reported on bko#15918 that on his machine ahci probing takes too
> long (well, if you ask me, that's not too long but anyways). This is
> caused by CAP_SSS disabling parallel scan. The code was added by
> Arjan in commit 886ad09fc83342aa1c5a02a0b6d3298b78a8067f. There is a
> module parameter to skip this but I'm curious whether the change was
> based on an actual problem as on most PC hardware by the time ahci
> driver kick in, the BIOS has spun up everything already.
This was based on Jeff's review comments on an earlier patch that did not use SSS.
The thing is, SSS means the system requests (well, demands) that we don't spin up the disks
up in parallel.... which we really really ought to honor... Jeff had a very valid point.
While today some bioses may spin everything up, that's not going to be the case going forward...
the industry as a whole is moving away from that (slowly but steadily).
next prev parent reply other threads:[~2010-05-06 9:30 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-06 8:22 ahci: CAP_SSS and parallel scan Tejun Heo
2010-05-06 9:30 ` Arjan van de Ven [this message]
2010-05-06 14:44 ` Tejun Heo
2010-05-06 19:49 ` Jeff Garzik
2010-05-07 5:14 ` Tejun Heo
2010-05-07 21:33 ` Jeff Garzik
2010-05-08 8:40 ` Tejun Heo
2010-05-08 21:53 ` Jeff Garzik
2010-05-06 20:19 ` Mark Lord
2010-05-07 5:16 ` Tejun Heo
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