* Re: AHCI_MAX_SG
[not found] <20050609090859.GO5140@suse.de>
@ 2005-08-20 6:45 ` Jeff Garzik
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From: Jeff Garzik @ 2005-08-20 6:45 UTC (permalink / raw)
To: Jens Axboe, linux-ide@vger.kernel.org
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
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[not found] <20050609090859.GO5140@suse.de>
2005-08-20 6:45 ` AHCI_MAX_SG Jeff Garzik
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