On Tue, Sep 15, 2009 at 12:10 AM, Bart Van Assche <bart.vanass...@gmail.com> wrote: > On Tue, Sep 15, 2009 at 1:03 AM, Chris Worley <worl...@gmail.com> wrote: >> >> On Mon, Sep 14, 2009 at 12:51 PM, Vladislav Bolkhovitin <v...@vlnb.net> >> wrote: >> > Chris Worley, on 09/11/2009 11:50 PM wrote: >> >> >> >> I've definitely removed the switch/firmware from being the cause. >> >> >> >> I'm thinking the reason you can't repeat the test may be latency >> >> related. We get ~50usecs average latency (on small block sizes), >> >> which can't be achieved using regular SSD's (and rotating drives are >> >> nowhere close). Maybe a ramdisk would help repeat the issue. >> > >> > I think you should try to reproduce the problem with ramdisk or nullio. By >> > so you will eliminate possible influence of the SSD backend. >> >> W/ 12GB RAM in the target, I created a 7GB ramdisk: >> >> mount -t ramfs -o size=7g ramfs /mnt/ >> dd if=/dev/zero of=/mnt/foo bs=1024k count=7000 >> echo "open ramdisk /mnt/foo" > /proc/scsi_tgt/vdisk/vdisk >> echo "add ramdisk 2" >/proc/scsi_tgt/groups/Default/devices >> >> Then, on the initiator, I tested it... and it hung during sequential >> 8KB block reads: >> >> fio --rw=read --bs=8k --numjobs=64 --iodepth=64 --sync=0 --direct=1 >> --randrepeat=0 \ >> --group_reporting --ioengine=libaio --filename=/dev/sde --name=test >> --loops=10000 --runtime=600 >> >> Note that I was running the SM on the target this time too. > > Which Linux distro was installed on the inititiator and on the target > ? And if applicable, which OFED version ? Which kernel messages were > logged by SRPT around the time the issue occurred (after having > enabled SRPT logging first) ?
As logging hadn't helped this issue previously, I've not been enabling it. That plus the kernel hacks needed to invoke logging, it's not worth enabling. This was with Ubuntu 8.10, built-in IB on the 2.6.27-14-server kernel. I couldn't get ramdisks working w/ SCST in RHEL5.2. When running: echo "open ramdisk /mnt/foo" > /proc/scsi_tgt/vdisk/vdisk I get the error: dev_vdisk: ***ERROR***: Wrong f_op or FS doesn't have required capabilities ... which doesn't occur in the Ubuntu kernel, so I've been unable to test RHEL kernels w/ ramdisks. In general, this problem occurs w/ 8KB and smaller blocks w/ the Ubuntu kernels, and 2KB and smaller blocks w/ RHEL kernels. Chris > > Bart. > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html