Date: Sat, 27 Jun 2009 13:05:00 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-current@freebsd.org Subject: Re: RFC: ATA to CAM integration patch Message-ID: <h24uct$5h9$1@ger.gmane.org> In-Reply-To: <20090627101151.GA40915@freebsd.org> References: <4A4517BE.9040504@FreeBSD.org> <20090627101151.GA40915@freebsd.org>
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Roman Divacky wrote: > On Fri, Jun 26, 2009 at 09:47:26PM +0300, Alexander Motin wrote: >> Hi. >> >> I would like to present for testing and feedback present state of my and >> Scott work on extending CAM subsystem to support ATA in addition to >> SCSI. At this moment we have: > > this is awesome! do you plan to add support for the TRIM command support? > what would it take to teach FreeBSD to use the TRIM? GEOM knows the BIO_DELETE command, which is supposed to do what TRIM does but is currently mostly unused. I think tree things need to happen to use TRIM effectively: 1) Investigate the conditions of use of TRIM - e.g. must TRIM be applied at special alignment on media (i.e. flash block-size?), because BIO_DELETE has no alignment requirements. 2) Translate BIO_DELETE into appropriate IO command(s) in the driver(s) 3) Make file systems use BIO_DELETE (or whatever comes from it). AFAIK it has been started for UFS, I have no idea about ZFS. 3a) See if existing GEOM classes support BIO_DELETE properly (i.e. passthrough to the lower classes)
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