On 5/25/11 4:47 AM, Lukas Czerner wrote: > unlinked often). Unfortunately xfs does not have this support yet, but > other filesystems do (ext4,btrfs,...) so if you like you might try one > of those and mount it with -o discard mount option. What it does is, > that it will send a TRIM for every range of freed filesystem blocks. > > Generally, in its current state it comes with quite big performance > loss (that's why we have fstrim), but in you case it might be actually > more convenient than running fstrim all the time. Also it is handled > automatically and the only think needed is to pass the "-i discard" > mount option. I have thought of using ext4 with the discard option on that device for just this reason. But this OCZ Revo SSD seems to execute TRIM rather slowly. I just timed it at 7 minutes 38 seconds to trim 46 GB of free space on a 90 GB SSD. I wouldn't want that to occur in the foreground while I'm running a program that's generating a lot of garbage blocks. Intel drives, at least, seem to execute TRIM much faster; I think they can take more blocks in each operation, and I conjecture that the drive controller simply adds them to a "to do" list for later erasure in the background. So there should probably be an option for "real-time" TRIM on those SSDs that can do it without a performance penalty. It would be nice if the fitrim ioctl were to issue TRIM commands only for newly created garbage blocks that haven't already been trimmed. But I guess that would require some major changes to the file system data structures. At the least, it would require some special record-keeping to keep track of this information. The Intel drive shows it's possible to implement a very speedy TRIM, so maybe it won't be such a bad thing to just trim the whole free list every time. Phil _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
