linux-kernel - Re: [PATCH v2 2/4] sched:Consider imbalance_pct when comparing loads in numa_has

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Message-ID: <20150623130114.GD32412@linux.vnet.ibm.com>
Date:	Tue, 23 Jun 2015 18:31:14 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Rik van Riel <riel@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, Mel Gorman <mgorman@...e.de>
Subject: Re: [PATCH v2 2/4] sched:Consider imbalance_pct when comparing loads
 in numa_has_capacity

* Ingo Molnar <mingo@...nel.org> [2015-06-23 10:10:39]:
> > Please let me know if there are any better ways to observe the
> > spread. [...]
> 
> There are. I see you are using prehistoric tooling, but see the various NUMA 
> convergence latency measurement utilities in 'perf bench numa':
> 
>   vega:~> cat numa01-THREAD_ALLOC
> 
>   perf bench numa mem --no-data_rand_walk -p 2 -t 16 -G 0 -P 0 -T 192 -l 1000 -zZ0c $@
> 
> You can generate very flexible setups of NUMA access patterns, and measure their 
> behavior accurately.
> 
> It's all so much more capable and more flexible than autonumabench ...

Okay, thanks for the hint, I will try this out in future.

> 
> Also, when you are trying to report numbers for multiple runs, please use 
> something like:
> 
>    perf stat --null --repeat 3 ...
> 
> This will run the workload 3 times (doing only time measurement) and report the 
> stddev in a human readable form.
> 

Thanks again for this hint. Wouldnt system time/ user time also matter?
I guess once Mel did point out that it was important to make sure that
system time and user time dont increase when elapsed time decreases. But
I cant find the email though.

-- 
Thanks and Regards
Srikar Dronamraju

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