Messages in this thread | | | Date | Mon, 20 May 2002 01:53:14 +0200 | From | Tomas Szepe <> | Subject | Re: Linux 2.4/2.5 SCSI considerably slower than FreeBSD |
| |
> > $ time sg_dd if=/dev/sg1 of=/dev/null bs=512 count=2m time=1 > > time to transfer data was 18.786448 secs, 57.16 MB/sec > > 2097152+0 records in > > 2097152+0 records out > > real 0m18.799s user 0m0.030s sys 0m3.010s > > In a live system (actually, it's idle, but every 5 s, there is a short > burst of disk activity -- reiserfs and ext3fs in use here, something is > going on there), sg_dd is not really better than plain dd: > > > time sg_dd if=/dev/sg0 of=/dev/null count=1310720 > > Assume default 'bs' (block size) of 512 bytes > > 1310720+0 records in > > 1310720+0 records out > > > > real 0m24.348s > > gives: 27,56 MB/s. A little better than dd, but still much less than FreeBSD's.
hmmm.
# sync; sync; time dd if=/dev/sda of=/dev/null bs=64k count=10000 10000+0 records in 10000+0 records out
real 0m12.809s user 0m0.020s sys 0m2.560s
(first read, the data shouldn't have been cached) -> 48.79 MB/s
I wouldn't suspect there's a problem, the numbers look reasonable.
$ uname -r 2.4.19-pre2
Disk: Host: scsi0 Channel: 00 Id: 02 Lun: 00 Vendor: SEAGATE Model: ST336706LW Rev: 0109 Type: Direct-Access ANSI SCSI revision: 03 (i.e., 36GiB 160MB/s Seagate Cheetah)
Controller - HP netserver onboard sym53c896.
T. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |