Jason Holmes wrote:
>
> Trond Myklebust wrote:
> >
> > Any hints on how I can reproduce your results?
>
> Unfortunately Gaussian's licensing would prohibit me from passing it
> along to reproduce this. I'll try to reproduce this with another
> program this morning and get back to you.
OK, I haven't found any other program that behaves similar to Gaussian
on this, but I did do a few more runs with 2.6.0-test9-bk17 vs 2.4.22,
one set with nfs_debug on and one set with rpc_debug on. I haven't
analyzed the files in depth (and doing so would really be beyond me at
this point), but on a "dumb" level, the nfs files are of similar length
in terms of lines, but the RPC file for 2.6.0-test9-bk17 is much larger:
[root@fs4 log]# wc -l kern.*
16236 kern.nfs-2.4.22
17188 kern.nfs-2.6.0-test9-bk17
20565 kern.rpc-2.4.22
32684 kern.rpc-2.6.0-test9-bk17
Note that there is probably some small amount of noise in these files,
but 98% of it should be from the Gaussian runs. I put them up at:
http://magicbus.cac.psu.edu/nfs
if you want to look at them. One small observation is that 2.4.22
reaches much larger values of cwnd than test9-bk17, resulting in a lot
fewer calls to functions such as xprt_cwnd_limited (1861 vs. 2715).
Whether or not this means anything, I don't know.
Trond, if none of this helps and you really want to debug this, I can
probably give you access to two machines to do so.
Thanks,
--
Jason Holmes
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>>>>> " " == Jason Holmes <[email protected]> writes:
> if you want to look at them. One small observation is that
> 2.4.22 reaches much larger values of cwnd than test9-bk17,
> resulting in a lot fewer calls to functions such as
> xprt_cwnd_limited (1861 vs. 2715). Whether or not this means
> anything, I don't know.
It means that the UDP throughput is slightly more stable. However the
thing that surprises me there is that in both cases 'xprt_cwnd_limited
cong = 0' is the dominant case. That means basically that you only
have one outstanding request on the wire at any point in time (there
are only a few cases where cong=256 => 2 requests, and cong=512 => 3
requests).
IOW this all appears to be doing synchronous I/O only (both in the
case of 2.4.22 and 2.6.0).
Note: most of these RPC calls do indeed appear to be something other
than WRITE calls. Are they perhaps GETATTR calls? Have you for
instance set 'noac', 'actimeo' or something like that?
Could you please try using
echo "9" >/proc/sys/sunrpc/nfs_debug
rather than echo "1". That should give us the debugging info from
nfs/read.c and nfs/write.c in addition to what you've already got.
Cheers,
Trond
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