Bob Friesenhahn <[email protected]> wrote:

> On Mon, 13 Jul 2009, Mike Gerdts wrote:
> >
> > FWIW, I hit another bug if I turn off primarycache.
> >
> > http://defect.opensolaris.org/bz/show_bug.cgi?id=10004
> >
> > This causes really abysmal performance - but equally so for repeat runs!
>
> It is quite facinating seeing the huge difference in I/O performance 
> from these various reports.  The bug you reported seems likely to be 
> that without at least a little bit of caching, it is necessary to 
> re-request the underlying 128K ZFS block several times as the program 
> does numerous smaller I/Os (cpio uses 10240 bytes?) across it. 

cpio reads/writes in 8192 byte chunks from the filesystem.

BTW: star by default creates a shared memory based FIFO of 8 MB size and
reads in the biggest possible size that would currently fit into the FIFO.

Jörg

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