On Mon, Mar 10, 2008 at 3:42 PM, Doron Shoham <[EMAIL PROTECTED]> wrote: > > Bart Van Assche wrote: > > Can you please try to use direct I/O instead of buffered I/O ? > > > > Bart. > > I have tried to use dio but when the bpt was 128 (or higher) I got the > following error: > > echo 1 > /proc/scsi/sg/allow_dio > > sgp_dd if=/dev/sg1 of=/dev/null bs=512 bpt=128 thr=8 time=1 count=5M dio=1 > time to transfer data was 2.236290 secs, 1200.36 MB/sec > 5242880+0 records in > 5242880+0 records out > >> Direct IO requested but incomplete 40960 times
I'm not familiar with the /proc/scsi/sg/allow_dio entry. I was referring to options like "iflag=direct" or "oflag=direct" for dd -- all performance tests I have performed in the past were with dd and xdd. Without direct I/O, read tests use Linux' buffering. If the amount of data being read is less than the available RAM, buffered I/O tests only measure how fast Linux can copy data in RAM. Bart. _______________________________________________ ewg mailing list ewg@lists.openfabrics.org http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ewg