From: Jeff Garzik <jgarzik@pobox.com>
To: Jens Axboe <axboe@suse.de>,
"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>
Subject: Re: AHCI_MAX_SG
Date: Sat, 20 Aug 2005 02:45:21 -0400 [thread overview]
Message-ID: <4306D181.5050205@pobox.com> (raw)
In-Reply-To: <20050609090859.GO5140@suse.de>
Jens Axboe wrote:
> Been wondering about this weird value for a while - why does it default
> to 168 segments? As clustering is disabled, that makes 672KiB the
> largest supported request. So currently the dma mapped controller
> command area is about 91KiB in size, I guess the limit is meant to limit
> the size of that area because 256 would be nicer. So how about making it
> 160 which makes the resulting command at least a multiple of 128, or
> even just 128 which gives us a nice clean 512KiB?
(I hope you don't mind me making a private message public -- several
people have asked this, and even you have brought this up in public)
168 is the number that guarantees that AHCI_PORT_PRIV_DMA_SZ is 4K.
No other reason, and, it can (and probably will) be increased in the future.
Jeff
parent reply other threads:[~2005-08-20 6:45 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20050609090859.GO5140@suse.de>]
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