[LTP] [PATCH v2] io: fix really slow dio_sparse on certain systems

[Cyril Hrubis]

Hi!
> I guess it's not about slow buffering. What I suppose happens is that
> every time the writer thread writes with O_DIRECT it invalidates the
> page cache and we have to re-read everything from disk. Which measn that
> the data are often removed from the cache between the reads and the
> reader processes are often forced to re-read the data from the disk. If
> there was no O_DIRECT reader thread the first child that happens to read
                         ^
			 writer

-- 
Cyril Hrubis
chrubis@suse.cz