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    SubjectRe: How to monitor Linux NFS client load?
    Date
    On Sunday 12 of July 2009 02:44:27 Trond Myklebust wrote:
    > On Sat, 2009-07-11 at 21:03 +0400, Andrey Borzenkov wrote:
    > > Recently we have the case of very high latencies on NFS reads as
    > > reported by application (SAP R/3). NFS server was NetApp FAS;
    > > according to NetApp statistic, average volume read latencies were
    > > in order 10ms, while SAP stats gave 30-50ms. Systems were
    > > interconnected by dedicated 1Gb/s Cisco switches (3750G) with ca.
    > > 30% max load on interfaces.
    > >
    > > On advice of my colleague we changed sunrpc.tcp_slot_table_entries
    > > from default 16 to 128 which seemed to make situation much better -
    > > without changing load pattern of filer in any visible way.
    > >
    > > Now, I can understand, why we observed much higher latency on
    > > system and why changing (what effectively is) queue depth helped.
    > > But I am totally frustrated that there does not appear to be *any*
    > > possibility to detect this situation on Linux side and to get a
    > > real numbers of real NFS IO latencies or number of requests waiting
    > > to be executed (and I do not even dream about per-mount point
    > > stats).
    > >
    > > I am grateful for any hints how can we monitor Linux NFS client and
    > > get real-life numbers of what happens inside. Thank you!
    >
    > See the nfs-iostat utility in the nfs-utils package:
    >
    > http://git.linux-nfs.org/?p=steved/nfs-utils.git;a=blob;f=tools/nfs-i
    >ostat/nfs-iostat.py;h=9626d42609b9485c7fda0c9ef69d698f9fa929fd;hb=HEAD
    >

    This looks exactly like what is required, except ...

    cn1:~ # ./nfs-iostat.py 2
    Traceback (most recent call last):
    File "./nfs-iostat.py", line 559, in ?
    iostat_command(prog)
    File "./nfs-iostat.py", line 464, in iostat_command
    mountstats = parse_stats_file('/proc/self/mountstats')
    File "./nfs-iostat.py", line 434, in parse_stats_file
    f = file(filename)
    IOError: [Errno 2] No such file or directory: '/proc/self/mountstats'

    Which minimum kernel version is required for it?

    Thank you!
    [unhandled content-type:application/pgp-signature]
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