On 2010.11.18 at 18:05 +0000, Jamie Lokier wrote: > Jeff Moyer wrote: > > James Bottomley <James.Bottomley@xxxxxxx> writes: > > > > > Not stepping into the debate: I'm happy to see punch go to the mapping > > > data and FITRIM pick it up later. > > > > > > However, I think it's time to question whether we actually still want to > > > allow online discard at all. Most of the benchmarks show it to be a net > > > > Define online discard, please. > > > > > lose to almost everything (either SSD or Thinly Provisioned arrays), so > > > it's become an "enable this to degrade performance" option with no > > > upside. > > > > Some SSDs very much require TRIMming to perform well as they age. If > > you're suggesting that we move from doing discards in journal commits to > > a batched discard, like the one Lukas implemented, then I think that's > > fine. If we need to reintroduce the finer-grained discards due to some > > hardware changes in the future, we can always do that. > > "Growable" virtual disks benefit from it too, if it frees up a lot of space. > > Windows has some ability to trim unused space in NTFS on virtual disks > for this reason; I'm not sure if it's an online or offline procedure. > > Online trim may be slow, but offline would be awfully inconvenient > when an fs is big and needed for a live system, or when it's your root fs. You can call FITRIM from a running system. Infact I run it once per week as a cron job on my (mounted) root fs. -- Markus -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
