On Thu, Nov 19, 2009 at 03:38:04AM +0900, OGAWA Hirofumi wrote: > Christoph Hellwig <hch@xxxxxx> writes: > > > Currently shipping discard capable SSDs and arrays have rather sub-optimal > > implementations of the command and can the use of it can cause massive > > slowdowns. Make issueing these commands option as it's already in btrfs > > and gfs2. > > Thanks. Looks good to me, I'll apply as is. > > BTW, what value is default for those users? And from users of some > filesystems, it might be better to do in lower layer or VFS? The situation is the following: As of 2.6.32-rc7: - btrfs needs the discard option to enable trim, it's off by default - gfs2 needs the discard option to enable trim, it's off by default - ext4 does discard by default, no option to disable - fat does discard by default, no option to disable - the swap code does discard by default, no option to disable Eric has a patch for ext4 to implement the btrfs/gfs2 semantics, and this is the one for fat. A discussion is ongoing about swap. I don't think moving block specific options is a good idea to do in the VFS. The other option would be to disable it in the block layer, but that's not alwas intuitive. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
