Hi Alja,
The way I read the graph is that when you put a bigger load on the proxy
server it slows down. I wouldn't think that is unusual. The proxy machine
may be overloaded at that point. It's unlikely to be the nic because we
know that it can do at least 360mbps. So it might be the CPU (easy to
check). Alternatively, it could be the disk drive at the end point that
is overloaded with 300 jobs.
But let's say the above isn't the case because 300 jobs in single read
perform better than 150 jobs in single read. That would point to the fact
that either proxy is unrolling the vector reads or that the server is
unrolling them. I suspect both because the readv passthrough is not
available until Release 4 which has not been released yet. Sever-side
unrolling, as unpleasant as it is, would not show such an effect but
proxy-side unrolling most certainly would.
The take-away: try the test again with a proxy server based on git head.
Andy
On Tue, 21 Jan 2014, Alja Mrak-Tadel wrote:
> Hi,
>
> There was an issue at RAL T1 where they are trying to use proxy server as
> their nodes do not have outgoing connectivity.
>
> Trying to reproduce this at UCSD, I have been running test on a proxy server
> without any caching using the following configuration file:
> http://uaf-2.t2.ucsd.edu/~alja/onlyproxy.cfg
>
>
> On the plot http://uaf-2.t2.ucsd.edu/~matevz/tmp/traffic.png is network
> traffic of the proxy server during four consecutive tests:
> - 300 jobs reading 2.4MB every 10s in 128 chunk-vector-read
> - 300 jobs reading 2.4MB every 10s in a single read
> - 150 jobs reading 2.4MB every 10s in a single read
> - 150 jobs reading 2.4MB every 10s in 128 chunk-vector-read
>
>
> Is there something obvious that we missed in the configuration of proxy-only
> server? How should we go about trying to find the bottlenecks here?
>
> Thanks,
> Alja
>
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