On Sun, 2008-11-23 at 05:35 -0700, Matthew Wilcox wrote: > The current VFAT filesystem implements DISCARD. As does btrfs. I think I posted ext2 patches a little while ago too? Or someone else did. Did they get merged? > Here's the patch I've > been testing -- it's not right; it causes SSDs from two different vendors > to hang. I'm waiting for a free slot on the SATA protocol analyser to > figure out what's we're doing wrong. > > Note that the SCSI UNMAP command does not yet have an official number, > so this patch cannot yet be applied (... how much longer until ATA is no > longer part of SCSI?) > > We don't attempt to put non-contiguous ranges into a single TRIM yet. We don't even merge contiguous ranges -- I still need to fix the elevators to stop writes crossing writes, before we can stop discards from also being barriers. (Discards are just writes, for the purpose of that conversation). > We currently assume all SCSI devices support UNMAP instead of checking > the feature flag (because last time I looked, I couldn't tell what flag > I was supposed to check). Once we do that, I need to set that flag in > libata-scsi depending on the support for the TRIM bit in the identify > command. The code in drivers/ide does check the feature, although I'm not 100% sure I got that part right. -- David Woodhouse Open Source Technology Centre David.Woodhouse@xxxxxxxxx Intel Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
