On Tue, Aug 14, 2012 at 3:22 PM, Josef Bacik <jbacik@xxxxxxxxxxxx> wrote: > Swinging this pendulum back the other way. We've been allocating chunks up > to 2% of the disk no matter how much we actually have allocated. So instead > fix this calculation to only allocate chunks if we have more than 80% of the > space available allocated. Please test this as it will likely cause all > sorts of ENOSPC problems to pop up suddenly. Thanks, > > Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxxxx> I've been testing this patch with my multiple rsync test (On a 3.5.1 kernel merged with for-linus). I tested without compression, and with lzo compression, and I haven't run into any ENOSPC issues. I still have ENOSPC issues with zlib, with or without this patch. I made a series of runs with and without this patch (on an uncompressed, newly formatted partition), and some of the results were not what I anticipated. 1) I found that *MORE* metadata space was being allocated with this patch than when using an unpatched baseline kernel. The total allocated space was exactly the same in each run (I saw a slight variation in the amount of used Metadata). On the unpatched baseline kernel, at the end of the run, the 'btrfs fi df' command would show: # btrfs fi df /mnt/benchmark/ Data: total=10.01GB, used=6.99GB System: total=4.00MB, used=4.00KB Metadata: total=776.00MB, used=481.38MB With this patch applied, the 'btrfs fi df' command would show: # btrfs fi df /mnt/benchmark/ Data: total=10.01GB, used=6.99GB System: total=4.00MB, used=4.00KB Metadata: total=1.01GB, used=480.94MB 2) The multiple rsync's would run significantly faster with the patched kernel. Unpatched baseline kernel: Time to run 7 rysncs: 348.3 sec (+/- 9.7 sec) Patched kernel: Time to run 7 rsyncs: 316.6 sec (+/- 6.5 sec) Perhaps the extra allocated metadata space made things run better, or perhaps something else was going on. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
