Date: Thu, 1 Dec 2011 10:56:35 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-stable@freebsd.org Cc: Daryl Sayers <daryl@ci.com.au>, Jeremy Chadwick <freebsd@jdc.parodius.com> Subject: Re: Low nfs write throughput Message-ID: <201112011056.35880.jhb@freebsd.org> In-Reply-To: <20111201053523.GA66988@icarus.home.lan> References: <201111180310.pAI3ARbZ075115@mippet.ci.com.au> <201111291036.44620.jhb@freebsd.org> <20111201053523.GA66988@icarus.home.lan>
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On Thursday, December 01, 2011 12:35:23 am Jeremy Chadwick wrote: > On Tue, Nov 29, 2011 at 10:36:44AM -0500, John Baldwin wrote: > > On Monday, November 28, 2011 7:12:39 pm Daryl Sayers wrote: > > > >>>>> "Bengt" == Bengt Ahlgren <bengta@sics.se> writes: > > > > > > > Daryl Sayers <daryl@ci.com.au> writes: > > > >> Can anyone suggest why I am getting poor write performance from my nfs setup. > > > >> I have 2 x FreeBSD 8.2-STABLE i386 machines with ASUS P5B-plus mother boards, > > > >> 4G mem and Dual core 3g processor using 147G 15k Seagate SAS drives with > > > >> onboard Gb network cards connected to an idle network. The results below show > > > >> that I get nearly 100Mb/s with a dd over rsh but only 15Mbs using nfs. It > > > >> improves if I use async but a smbfs mount still beats it. I am using the same > > > >> file, source and destinations for all tests. I have tried alternate Network > > > >> cards with no resulting benefit. > > > > > > > [...] > > > > > > >> Looking at a systat -v on the destination I see that the nfs test does not > > > >> exceed 16KB/t with 100% busy where the other tests reach up to 128KB/t. > > > >> For the record I get reads of 22Mb/s without and 77Mb/s with async turned on > > > >> for the nfs mount. > > > > > > > On an UFS filesystem you get NFS writes with the same size as the > > > > filesystem blocksize. So an easy way to improve performance is to > > > > create a filesystem with larger blocks. I accidentally found this out > > > > when I had two NFS exported filesystems from the same box with 16K and > > > > 64K blocksizes respectively. > > > > > > > (Larger blocksize also tremendously improves the performance of UFS > > > > snapshots!) > > > > > > Thanks to all that answered. I did try the 'sysctl -w vfs.nfsrv.async=1' with > > > no reportable change in performance. We are using a UFS2 filesystem so the > > > zfs command was not required. I did not try the patch as we would like to stay > > > as standard as possible but will upgrade if the patch is released in new > > > kernel. > > > > If you can test the patch then it is something I will likely put into the > > next release. I have already tested it as far as robustness locally, what > > I don't have are good performance tests. It would really be helpful if you > > were able to test it. > > John, > > We'd like to test this patch[1], but need to know if it needs to be > applied to just the system acting as the NFS server, or the NFS clients > as well. > > [1]: http://www.freebsd.org/~jhb/patches/nfs_server_cluster.patch Just the NFS server. I'm going to commit it to HEAD later today. -- John Baldwin
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