Chris Worley, on 09/15/2009 03:03 AM 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.
Should you try then with iSCSI with IPoIB? It will eliminate the SRP stack.
Thanks,
Chris
Vlad
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