From: Tejun Heo <htejun@gmail.com>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: "zhao, forrest" <forrest.zhao@intel.com>, linux-ide@vger.kernel.org
Subject: Re: [RFC] AHCI Command Completion Coalescing(CCC) proposal
Date: Fri, 09 Jun 2006 12:43:37 +0900 [thread overview]
Message-ID: <4488EE69.7050907@gmail.com> (raw)
In-Reply-To: <4488EB4A.4050501@pobox.com>
Jeff Garzik wrote:
> I'm still not sure I follow you?
>
> When AHCI runs out of commands to execute, it transitions from H:Idle to
> Ccc:SetIS.
>
> IMPORTANT NOTE: In order for CCC to be effective on AHCI, ahci.c and
> libata (and sata_sil24) must be updated to support queuing a list of
> non-NCQ commands onto the controller, and recovering from errors in the
> case where a command list full of non-NCQ commands is present.
I thought about it but am not really sure whether it's worth the
trouble. We'll be saving on inter-command latency and interrupt
handling which is great but not so sure how noticeable the improvement
would be. NCQ is already all around. How about doing CCC only during
NCQ command phase?
Hmmm... maybe those SSDs would benefit from CCC during non-NCQ commands
though if they don't support NCQ, which they don't really need.
--
tejun
next prev parent reply other threads:[~2006-06-09 3:43 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-08 7:30 [RFC] AHCI Command Completion Coalescing(CCC) proposal zhao, forrest
2006-06-08 15:01 ` Jeff Garzik
2006-06-09 2:27 ` zhao, forrest
2006-06-09 3:11 ` Another project for you... :) Jeff Garzik
2006-06-09 3:13 ` zhao, forrest
2006-06-09 22:29 ` Greg Freemyer
2006-06-09 23:44 ` Alan Cox
2006-06-09 3:43 ` [RFC] ATA host-protected area (HPA) device mapper? Jeff Garzik
2006-06-09 4:51 ` Matthew Frost
2006-06-14 8:01 ` Another project for you... :) zhao, forrest
2006-06-14 15:19 ` Randy.Dunlap
2006-06-15 7:59 ` zhao, forrest
2006-06-15 11:47 ` Jeff Garzik
2006-06-09 3:30 ` [RFC] AHCI Command Completion Coalescing(CCC) proposal Jeff Garzik
2006-06-09 3:39 ` zhao, forrest
2006-06-09 3:43 ` Tejun Heo [this message]
2006-06-09 3:47 ` Tejun Heo
2006-06-09 3:51 ` zhao, forrest
2006-06-09 4:12 ` Jeff Garzik
2006-06-09 5:24 ` Tejun Heo
2006-06-09 11:49 ` Jens Axboe
2006-06-09 3:53 ` Jeff Garzik
2006-06-09 3:52 ` Jeff Garzik
2006-06-09 11:49 ` Jens Axboe
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