On 2011-06-30 18:35, Trond Myklebust wrote: > On Thu, 2011-06-30 at 18:13 +0300, Benny Halevy wrote: >> On 2011-06-30 17:24, Trond Myklebust wrote: >>> On Thu, 2011-06-30 at 09:36 -0400, Andy Adamson wrote: >>>> On Jun 29, 2011, at 10:32 PM, quanli gui wrote: >>>> >>>>> When I use the iperf tools for one client to 4 ds, the network >>>>> throughput is 890MB/S. It reflect that it is indeed 10GE non-blocking. >>>>> >>>>> a. about block size, I use bs=1M when I use dd >>>>> b. we indeed use the tcp (doesn't the nfsv4 use the tcp defaultly?) >>>>> c. the jumbo frames is what? how set mtu automatically? >>>>> >>>>> Brian, do you have some more tips? >>>> >>>> 1) Set the mtu on both the client and the server 10G interface. Sometimes 9000 is too high. My setup uses 8000. >>>> To set MTU on interface eth0. >>>> >>>> % ifconfig eth0 mtu 9000 >>>> >>>> iperf will report the MTU of the full path between client and server - use it to verify the MTU of the connection. >>>> >>>> 2) Increase the # of rpc_slots on the client. >>>> % echo 128 > /proc/sys/sunrpc/tcp_slot_table_entries >>>> >>>> 3) Increase the # of server threads >>>> >>>> % echo 128 > /proc/fs/nfsd/threads >>>> % service nfs restart >>>> >>>> 4) Ensure the TCP buffers on both the client and the server are large enough for the TCP window. >>>> Calculate the required buffer size by pinging the server from the client with the MTU packet size and multiply the round trip time by the interface capacity >>>> >>>> % ping -s 9000 server - say 108 ms average >>>> >>>> 10Gbits/sec = 1,250,000,000 Bytes/sec * .108 sec = 135,000,000 bytes >>>> >>>> Use this number to set the following: >>>> sysctl -w net.core.rmem_max = 135000000 >>>> sysctl -w net.core.wmem_max 135000000 >>>> sysctl -w "net.ipv4.tcp_rmem <first number unchaged> <second unchanged> 135000000" >>>> sysctl net.ipv4.tcp_wmem <first number unchaged> <second unchanged> 135000000" >>>> >>>> 5) mount with rsize=131072,wsize=131072 >>> >>> 6) Note that NFS always guarantees that the file is _on_disk_ after >>> close(), so if you are using 'dd' to test, then you should be using the >>> 'conv=fsync' flag (i.e 'dd if=/dev/zero of=test count=20k conv=fsync') >>> in order to obtain a fair comparison between the NFS and local disk >>> performance. Otherwise, you are comparing NFS and local _pagecache_ >>> performance. >> >> FWIW, modern versions of gnu dd (not sure exactly which version changed that) >> calculate and report throughput after close()ing the output file. > > ...but not after syncing it unless you explicitly request that. > > On most (all?) local filesystems, close() does not imply fsync(). Right. My point is that for benchmarking NFS, conv=fsync won't show any noticeable difference. We're in complete agreement that it's required for benchmarking local file system performance. Benny > > Trond -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
