From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: [Scst-devel] [ofa-general] WinOF_2_0_5/SRP initiator: slow reads and eventually hangs Date: Tue, 15 Sep 2009 20:43:25 +0400 Message-ID: <4AAFC42D.4030708@vlnb.net> References: <4AA4F561.504@vlnb.net> <4AAE909F.6030202@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Chris Worley Cc: Bart Van Assche , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, scst-devel , OpenIB List-Id: linux-rdma@vger.kernel.org Chris Worley, on 09/15/2009 07:50 PM wrote: > On Tue, Sep 15, 2009 at 12:10 AM, Bart Van Assche > wrote: >> On Tue, Sep 15, 2009 at 1:03 AM, Chris Worley wrote: >>> On Mon, Sep 14, 2009 at 12:51 PM, Vladislav Bolkhovitin 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. Use ramfs instead. > Chris >> Bart. >> > > ------------------------------------------------------------------------------ > Come build with us! The BlackBerry® Developer Conference in SF, CA > is the only developer event you need to attend this year. Jumpstart your > developing skills, take BlackBerry mobile applications to market and stay > ahead of the curve. Join us from November 9-12, 2009. Register now! > http://p.sf.net/sfu/devconf > _______________________________________________ > Scst-devel mailing list > Scst-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org > https://lists.sourceforge.net/lists/listinfo/scst-devel > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html