Date: Thu, 07 Jul 2005 11:30:24 +0200 From: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk> To: Luigi Rizzo <rizzo@icir.org> Cc: current@FreeBSD.ORG Subject: Re: disksort disappeared from ATA devices in HEAD ? Message-ID: <42CCF630.5070308@DeepCore.dk> In-Reply-To: <20050706143050.A96472@xorpc.icir.org> References: <20050706143050.A96472@xorpc.icir.org>
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Luigi Rizzo wrote: > I notice that the ata drivers in HEAD do not use anymore > bioq_disksort, but rather they have their own routine, > (ad_queue_request() in turn calling ata_sort_queue()) > which probably does something similar. >=20 > I wonder: > 1) how different is ata_sort_queue() from bioq_disksort() > in terms of design ? The difference is that ata_sort_queue() has a way to make certain that=20 new requests are inserted after a specific point in the ATA queue=20 (freezepoint). It also knows how to deal with non-r/w operations. This is needed to make "composite" ATA operations work properly.=20 Composite ATA operations are several ATA operations chained together=20 over different ATA channels, which are *real* handy for RAID operations e= tc. > 2) is there any strong reason for this change ? Since this is special usage for ATA ops alone I didn't want to pollute=20 the system disksort with this functionality. If/when we grow a way to=20 register specialized sort routines with the system that could perhaps be = used then. > 3) any pointers to mail threads where this changes have been > discussed ? Nope. This was my decision during the development of ATA mkIII. -- -S=F8ren
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