[Openstack] Writes are faster than reads in Swift

Michael Barton mike-launchpad at weirdlooking.com
Wed Dec 14 04:32:59 UTC 2011

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.


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
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