John-Mark Gurney wrote this message on Fri, Oct 17, 2014 at 09:58 -0700: > Sourish Mazumder wrote this message on Fri, Oct 17, 2014 at 17:34 +0530: > > I am planning to use geom gate network for accessing remote disks. I set up > > geom gate as per the freebsd handbook. I am using freebsd 9.2. > > I am noticing heavy performance impact for disk IO when using geom gate. I > > am using the dd command to directly write to the SSD for testing > > performance. The IOPS gets cut down to 1/3 when accessing the SSD remotely > > over a geom gate network, compared to the IOPS achieved when writing to the > > SSD directly on the system where the SSD is attached. > > I thought that there might be some problems with the network, so decided to > > create a geom gate disk on the same system where the SSD is attached. This > > way the IO is not going over the network. However, in this use case I > > noticed the IOPS get cut down to 2/3 compared to IOPS achieved when writing > > to the SSD directly. > > > > So, I have a SSD and its geom gate network disk created on the same node > > and the same IOPS test using the dd command gives 2/3 IOPS performance for > > the geom gate disk compared to running the IOPS test directly on the SSD. > > > > This points to some performance issues with the geom gate itself. > > Not necessarily... Yes, it's slower, but at the same time, you now have > to run lots of network and TCP code in addition to the IO for each and > every IO... > > > Is anyone aware of any such performance issues when using geom gate network > > disks? If so, what is the reason for such IO performance drop and are there > > any solutions or tuning parameters to rectify the performance drop? > > > > Any information regarding the same will be highly appreciated. > > I did some work at this a while back... and if you're interested in > improving performance and willing to do some testing... I can send you > some patches.. > > There are a couple issues that I know about.. > > First, ggate specificly sets the buffer sizes, which disables the > autosizing of TCP's window.. This means that if you have a high latency, > high bandwidth link, you'll be limited to 128k / rtt of bandwidth. > > Second is that ggate isn't issueing multiple IOs at a time. This means > that any NCQ or tagging isn't able to be used, where as when running > natively they can be used...
I've attached a patch I would like other ggate users to test and verify that there aren't bugs, or performance regressions by using this patch. The patch is also available at: https://www.funkthat.com/~jmg/patches/ggate.patch -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not." _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
