Re: Performance Issues

[Rob Spanton <rob@robspanton.com>]

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Hi Everyone,

I wrote:
> I have a particularly uncomplicated setup (a desktop PC with a hard
> disk) and I'm seeing particularly slow performance from btrfs.  A `git
> status` in the linux source tree takes about 46 seconds after dropping
> caches, whereas on other machines using ext4 this takes about 13s.  My
> mail client (evolution) also seems to perform particularly poorly on
> this setup, and my hunch is that it's spending a lot of time waiting on
> the filesystem.

So I recently upgraded my desktop (now an i7-5820K on a Gigabyte
GA-X99-UD4 motherboard with 32GB of RAM), and moved the disk with this
problematic filesystem across to it.  With this new setup, I still get
reasonably poor performance: the git status now takes ~26 seconds after
dropping caches.  (Although note that this git repo has had been
repacked since I did the above benchmarks.)

I have also had the disk out on a USB-to-SATA adapter plugged into my
laptop, and seen similarly poor results.

So I've put the output of this command:

        trace-cmd record -T -e sched:sched_switch -o /tmp/trace.dat git status

Here: http://robspanton.com/2014/10/trace.dat.xz

If anyone has any further ideas about how to remedy this situation,
please do let me know!

Cheers,

Rob

(Not subscribed to this list, so please CC me.)


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