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? |