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From "ole ersoy" <ole.er...@gmail.com>
Subject Re: Benchmarks feedback
Date Mon, 26 Mar 2007 23:39:12 GMT
I wonder if disk access could be the bottle neck?

Would be interesting to see what happens if we get
a memory resident partition and run the same test against that.

Would be really sweet to get the whole box humming.  Thanks Matt and
Emmanuel!
It's great to be aware of this type of stuff.  I have a couple of 20 cpu
servers in my closet,
but  I have not had a chance to dust them off yet (Yeah, umhummm, sure).

Cheers,
- Ole



On 3/26/07, Emmanuel Lecharny <elecharny@gmail.com> wrote:
>
> Hi,
>
> I have done some benchmarks on the powerfull server on which Matt was
> kind enough to give me an access (8 dual core CPUs, 11 131 mogomips, 20
> Gb mem !).
>
> The results are pretty preliminary, and a little bit disappointing. Here
> are the tests I did :
>
> - 4 clients requesting the server;
> - each client doing 10 000 random requests for each run;
> - 12 runs for each client with a fixed number of thread;
> - a number of thread being 1, 2, 4, 5, 8, 10, 20 and 50.
>
> the best result I reached was around 1600 req/s, CPU peaked to 300 %
> (which means that no more than 3 cpus out of 16 where used), a maximum
> of 20% total CPU out of which 2,5% system. Not exactly brillant.
>
> I would have excpected that the CPU would have been more working more,
> so I guess something is wrong (contention, or not enough threads, or
> threads not being distributed enough, or simply not enough clients ).
>
> The last point (not enough client) should not be the reason : with only
> one client, I almost reached the same level of performance, and each new
> client added does not make a lot of difference (maybe 10% more requests
> being fulfilled ...)
>
> I don't think either that threads are not correctly distributed on the
> CPUs, because I tried with Sun JVM and Jrockit, and I get similar
> results, always above 250% (which means that threads are really
> distributed). However, I have no idea on how to know which CPU is a
> thread running on (any clue ?)
>
> So, contention. I did some other tests :
> 1) always requesting the same entry
> 2) requesting the rootDSE only
>
> Both tests should be running without any disk access (any idea on how to
> get some info about disk access, btw ?). Here are the results (same
> clients, same number of requests
> 1) same entry : around 4500 req/s, which is 3 times the number with
> random searches. CPU peaked to 400%, no more...
> 2) rootDSE : 11500 req/s. Same CPU peak.
>
> I have one more test to run, I want to setup a higher cache size, to see
> if it has some impact on the first scenario results.
>
> Ok, I will really appreciates any idea, any suggestion, any information
> whcih can help to find out why we are so limited.
>
> Thanks a lot for the server, Matt, this is really helpfull ! You will
> deserve a bunch of beers in may :) (let's say one beer for eacj thousand
> requests per second we can get :)
>
> Emmanuel
>

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