Date: Sat, 20 Oct 2012 15:52:03 +0300 From: Nikolay Denev <ndenev@gmail.com> To: Ivan Voras <ivoras@freebsd.org> Cc: "freebsd-hackers@freebsd.org Hackers" <freebsd-hackers@freebsd.org>, Rick Macklem <rmacklem@uoguelph.ca> Subject: Re: NFS server bottlenecks Message-ID: <942B9B96-7F2B-4833-865F-33DDCCA3500A@gmail.com> In-Reply-To: <CAF-QHFWY0drcrUpo7GGD1zQNSDWsEeB_LHAjEbUKrX2ovQHNxw@mail.gmail.com> References: <937460294.2185822.1350093954059.JavaMail.root@erie.cs.uoguelph.ca> <302BF685-4B9D-49C8-8000-8D0F6540C8F7@gmail.com> <k5gtdh$nc0$1@ger.gmane.org> <0857D79A-6276-433F-9603-D52125CF190F@gmail.com> <CAF-QHFUU0hhtRNK1_p9zks2w%2Be22bfWOtv%2BXaqgFqTiURcJBbQ@mail.gmail.com> <6DAAB1E6-4AC7-4B08-8CAD-0D8584D039DE@gmail.com> <23D7CB3A-BD66-427E-A7F5-6C9D3890EE1B@gmail.com> <CAF-QHFWY0drcrUpo7GGD1zQNSDWsEeB_LHAjEbUKrX2ovQHNxw@mail.gmail.com>
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On Oct 20, 2012, at 3:11 PM, Ivan Voras <ivoras@freebsd.org> wrote: > On 20 October 2012 13:42, Nikolay Denev <ndenev@gmail.com> wrote: >=20 >> Here are the results from testing both patches : = http://home.totalterror.net/freebsd/nfstest/results.html >> Both tests ran for about 14 hours ( a bit too much, but I wanted to = compare different zfs recordsize settings ), >> and were done first after a fresh reboot. >> The only noticeable difference seems to be much more context switches = with Ivan's patch. >=20 > Thank you very much for your extensive testing! >=20 > I don't know how to interpret the rise in context switches; as this is > kernel code, I'd expect no context switches. I hope someone else can > explain. >=20 > But, you have also shown that my patch doesn't do any better than > Rick's even on a fairly large configuration, so I don't think there's > value in adding the extra complexity, and Rick knows NFS much better > than I do. >=20 > But there are a few things other than that I'm interested in: like why > does your load average spike almost to 20-ties, and how come that with > 24 drives in RAID-10 you only push through 600 MBit/s through the 10 > GBit/s Ethernet. Have you tested your drive setup locally (AESNI > shouldn't be a bottleneck, you should be able to encrypt well into > Gbyte/s range) and the network? >=20 > If you have the time, could you repeat the tests but with a recent > Samba server and a CIFS mount on the client side? This is probably not > important, but I'm just curious of how would it perform on your > machine. I've now started this test locally. But from previous different iozone runs, I remember locally the speed = was much better, but I will wait for this test to finish, as the comparison will be = better. But I think there is still something fishy=85 I have cases where I have = reached 1000MB/s over NFS (from network stats, not local machine stats), but sometimes it is very = slow even for=20 file completely in ARC. Rick mentioned that this could be due to RPC = overhead and network round trip time, but earlier in this thread I've done a test only on the server by mounting = the NFS exported ZFS dataset locally and did some tests with "dd": > To take the network out of the equation I redid the test by mounting = the same filesystem over NFS on the server: >=20 > [18:23]root@goliath:~# mount -t nfs -o = rw,hard,intr,tcp,nfsv3,rsize=3D1048576,wsize=3D1048576 = localhost:/tank/spa_db/undo /mnt > [18:24]root@goliath:~# dd if=3D/mnt/data.dbf of=3D/dev/null bs=3D1M=20 > 30720+1 records in > 30720+1 records out > 32212262912 bytes transferred in 79.793343 secs (403696120 bytes/sec) > [18:25]root@goliath:~# dd if=3D/mnt/data.dbf of=3D/dev/null bs=3D1M > 30720+1 records in > 30720+1 records out > 32212262912 bytes transferred in 12.033420 secs (2676900110 bytes/sec) >=20 > During the first run I saw several nfsd threads in top, along with dd = and again zero disk I/O. > There was increase in memory usage because of the double buffering = ARC->buffercahe. > The second run was with all of the nfsd threads totally idle, and read = directly from the buffercache.
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