Thanks Peter for your explanation, and Benny for this option I was not aware of. Let me run some tests with this option. Regards, - KK linux-nfs-owner@xxxxxxxxxxxxxxx wrote on 06/19/2008 06:22:42 PM: > On Jun. 19, 2008, 15:04 +0300, Peter Staubach <staubach@xxxxxxxxxx> wrote: > > Krishna Kumar2 wrote: > >>> 200 processes: > >>> > >> By "200 processes", I meant 200 dd's, each reading from /dev/zero and > >> writing to a file on the filesystem. The script "nfs" was run twice, first > >> with > >> a local filesystem and the second time with the same filesystem NFS > >> mounted. > >> > >> > > > > Well, you aren't exactly comparing apples to apples. The NFS > > client does close-to-open semantics, meaning that it writes > > all modified data to the server on close. The dd commands run > > on the local file system do not. You might trying using > > something which does an fsync before closing so that you are > > making a closer comparison. > > try dd conv=fsync ... > > Benny > > > > > All that said, yes, one would expect a slow down. How much is > > debatable and varies from platform to platform and load to load. > > > > I would also advise care when running NFS like that. It is > > subject to deadlock and is not recommended. > > > > ps > > > >> Thanks, > >> > >> - KK > >> > >> linux-nfs-owner@xxxxxxxxxxxxxxx wrote on 06/19/2008 12:16:23 PM: > >> > >> > >>> Hi, > >>> > >>> I am running 2.6.25 kernel on a [4 way, 3.2 x86_64, 4GB] system. The test > >>> is doing I/O on a local ext3 filesystem, and measuring the bandwidth, and > >>> then NFS mounting the filesystem loopback on the same system. I have > >>> configured 64 nfsd's to run. The test script is attached at the bottom. > >>> > >>> My configuration is: > >>> /dev/some-local-disk : /local > >>> NFS mount /local : /nfs > >>> > >>> The result is: > >>> 200 processes: > >>> /local: 108000 KB/s > >>> /nfs: 66000 KB/s: Drop of 40% > >>> > >>> 300 processes (KB/s): > >>> /local: 112000 KB/s > >>> /nfs: 57000 KB/s: Drop of 50% > >>> > >>> I am not using any tuning, though I have tested with both > >>> sunrpc.tcp_slot_table_entries=16 & 128 > >>> > >>> Is this big a drop expected for a loopback NFS mount? Any > >>> feedback/suggestions are very > >>> appreciated. > >>> > >>> Thanks, > >>> > >>> - KK > >>> > >>> (See attached file: nfs)[attachment "nfs" deleted by Krishna > >>> > >> Kumar2/India/IBM] > >> > >> -- > >> 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 > >> > > > > -- > > 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 > > > -- > Benny Halevy > Software Architect > Tel/Fax: +972-3-647-8340 > Mobile: +972-54-802-8340 > bhalevy@xxxxxxxxxxx > > Panasas, Inc. > The Leader in Parallel Storage > www.panasas.com > -- > 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 -- 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
