Date: Mon, 20 Oct 2014 19:09:14 +0530 From: Sourish Mazumder <sourish@cloudbyte.com> To: Sourish Mazumder <sourish@cloudbyte.com>, freebsd-geom@freebsd.org Subject: Re: geom gate network Message-ID: <CABv3qbEVwKMn3dKbjtx=ASVo5Jaqfk3_jxvFXUUb%2B=N5gAMTqA@mail.gmail.com> In-Reply-To: <20141017165849.GX1852@funkthat.com> References: <CABv3qbGL99NZvQ-2Ze=rnQTjEEf_KLy1sJQHLV27e47sX2dLGw@mail.gmail.com> <20141017165849.GX1852@funkthat.com>
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I am willing to test out the patches on my setup. Please send me the patches. On Fri, Oct 17, 2014 at 10:28 PM, John-Mark Gurney <jmg@funkthat.com> wrote: > 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... > > -- > John-Mark Gurney Voice: +1 415 225 5579 > > "All that I will do, has been done, All that I have, has not." > -- Sourish Mazumder 9986309755
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