On Fri, 17 Feb 2005, Greg Stark wrote:
>
> Oliver Jowett <oliver@opencloud.com> writes:
>
>> So Linux is indeed doing a cache flush on fsync
>
> Actually I think the root of the problem was precisely that Linux does not
> issue any sort of cache flush commands to drives on fsync.
No, it does. Let's try the simplest test:
for (i = 0; i < LEN; i++) { write (fd, buf, 512); if (sync) fsync (fd);
}
with sync = 0 and 1, and you'll see the difference.
> There was some talk
> on linux-kernel of what how they could take advantage of new ATA features
> planned on new SATA drives coming out now to solve this. But they didn't seem
> to think it was urgent or worth the performance hit of doing a complete cache
> flush.
It was a bit different topic.
Regards,
E.R.
_________________________________________________________________________
Evgeny Rodichev Sternberg Astronomical Institute
email: er@sai.msu.su Moscow State University
Phone: 007 (095) 939 2383
Fax: 007 (095) 932 8841 http://www.sai.msu.su/~er