At Matt's request, I did some further experiments and have found that this appears to be particular to your hardware. This is not a general 32-bit problem. I re-ran this experiment on a 1-disk pool using a 32 and 64-bit kernel. I got identical results:
64-bit ====== $ /usr/bin/time dd if=/testpool1/filebench/testfile of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out real 20.1 user 0.0 sys 1.2 62 Mb/s # /usr/bin/time dd if=/dev/dsk/c1t3d0 of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out real 19.0 user 0.0 sys 2.6 65 Mb/s 32-bit ====== /usr/bin/time dd if=/testpool1/filebench/testfile of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out real 20.1 user 0.0 sys 1.7 62 Mb/s # /usr/bin/time dd if=/dev/dsk/c1t3d0 of=/dev/null bs=128k count=10000 10000+0 records in 10000+0 records out real 19.1 user 0.0 sys 4.3 65 Mb/s -j On Wed, May 16, 2007 at 09:32:35AM -0700, Matthew Ahrens wrote: > Marko Milisavljevic wrote: > >now lets try: > >set zfs:zfs_prefetch_disable=1 > > > >bingo! > > > > r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device > > 609.0 0.0 77910.0 0.0 0.0 0.8 0.0 1.4 0 83 c0d0 > > > >only 1-2 % slower then dd from /dev/dsk. Do you think this is general > >32-bit problem, or specific to this combination of hardware? > > I suspect that it's fairly generic, but more analysis will be necessary. > > >Finally, should I file a bug somewhere regarding prefetch, or is this > >a known issue? > > It may be related to 6469558, but yes please do file another bug report. > I'll have someone on the ZFS team take a look at it. > > --matt > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
