[Openstack] Writes are faster than reads in Swift

Huang Zhiteng winston.d at gmail.com
Wed Dec 14 05:21:06 UTC 2011


Can anyone explain why Swift doesn't want to utilize page cache _at all_?

On Wed, Dec 14, 2011 at 12:32 PM, Michael Barton <
mike-launchpad at weirdlooking.com> wrote:

> I can't explain it off the top of my head.
>
> I don't have a swift installation to play with at the moment, but it's
> conceivable that posix_fadvise is slower than we expect (drop_cache is
> called more frequently during reads than writes, iirc).  That could be
> tested by making drop_cache a no-op in the object server.
>
> Or running the object server under a profiler during both operations
> might shed some light on what is taking so much time.
>
> --Mike
>
>
>
> On Mon, Dec 12, 2011 at 8:44 AM, Zhenhua (Gerald) Guo <jenvor at gmail.com>
> wrote:
> > Hi, folks
> >  Recently, I have run some read/write tests for large files (400GB)
> > in Swift.  I found that writes were always faster than reads, which is
> > kinda counter-intuitive. What may be the cause?
> >  Has anyone else seen the same problem?
> >
> > Gerald
> >
> > _______________________________________________
> > Mailing list: https://launchpad.net/~openstack
> > Post to     : openstack at lists.launchpad.net
> > Unsubscribe : https://launchpad.net/~openstack
> > More help   : https://help.launchpad.net/ListHelp
>
> _______________________________________________
> Mailing list: https://launchpad.net/~openstack
> Post to     : openstack at lists.launchpad.net
> Unsubscribe : https://launchpad.net/~openstack
> More help   : https://help.launchpad.net/ListHelp
>



-- 
Regards
Huang Zhiteng
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack/attachments/20111214/8be8bd5f/attachment.html>


More information about the Openstack mailing list