openstack team mailing list archive

[Huang Zhiteng <winston.d@xxxxxxxxx>]

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@xxxxxxxxxxxxxxxx> 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@xxxxxxxxx>
> 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
> >
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-- 
Regards
Huang Zhiteng