[Sheepdog] [PATCH 3/3] store: use fallocate when allocating new objects

[MORITA Kazutaka]

At Fri, 11 Nov 2011 06:59:42 -0500,
Christoph Hellwig wrote:
> 
> On Fri, Nov 11, 2011 at 08:41:25PM +0900, MORITA Kazutaka wrote:
> > ==
> > 
> > 
> > The result was as follows:
> > 
> >   $ time ./a.out temp pwrite
> >   
> >   real   0m0.244s
> >   user   0m0.000s
> >   sys    0m0.008s
> > 
> >   $ time ./a.out temp fallocate
> >   
> >   real   0m43.050s
> >   user   0m0.000s
> >   sys    0m0.060s
> 
> Wow, I wonder what glibc is doing there given that you write the
> whole block.
> 
> > I guess posix_fallocate() causes a severe performance problem under
> > the circumstances that write is slow, because it calls lots of
> > pwrite() for each ext3 block when fallocate() is not available.
> 
> Ok.  Do you want a patch using fallocate and keeping the existing
> fallback for now?

Yes, please. :)

Thanks.

Kazutaka