On 01/24/2014 02:34 AM, Liu Bo wrote:
On Thu, Jan 23, 2014 at 01:07:52PM -0500, Josef Bacik wrote:
On one of our gluster clusters we noticed some pretty big lag spikes. This
turned out to be because our transaction commit was taking like 3 minutes to
complete. This is because we have like 30 gigs of metadata, so our global
reserve would end up being the max which is like 512 mb. So our throttling code
would allow a ridiculous amount of delayed refs to build up and then they'd all
get run at transaction commit time, and for a cold mounted file system that
could take up to 3 minutes to run. So fix the throttling to be based on both
the size of the global reserve and how long it takes us to run delayed refs.
This patch tracks the time it takes to run delayed refs and then only allows 1
seconds worth of outstanding delayed refs at a time. This way it will auto-tune
itself from cold cache up to when everything is in memory and it no longer has
to go to disk. This makes our transaction commits take much less time to run.
Thanks,
Which version of btrfs is the patch made for?
I checked the code and it doesn't seem to be btrfs-next, either...we don't
have a __btrfs_run_delayed_refs().
It depends on the patch I sent before where I move delayed refs onto a
delayed ref head rb tree. Thanks,
Josef
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