[PATCH v2] add concurrent malloc benchmark

[Siddhesh Poyarekar]

On Mon, Mar 09, 2015 at 11:02:22AM +0100, Leonhard Holz wrote:
> The current malloc benchtest does use multiple threads, but they work on
> independent block lists so that every thread uses its own arena only. The
> following patch adds a version of the benchmark with all threads working on
> the same block list, so that it is likely that a thread free()s a block in
> an arena of a different thread and by this causes lock contentation on that
> arena. Therefore the performance of the malloc locking mechanism is included
> in the measuring.
> 
> Unfortunately the access to an entry in the shared block list has to be
> protected by a mutex. The time taken for acquiring the mutex is included in
> the measured time per iteration, so that the iteration time of the
> concurrent malloc benchmark is not directly compareable the time of the
> per-thread benchmark.

It might be a better idea to simulate producers and consumers for such
a benchmark.  Size variance is not an issue in this case since we're
not measuring overhead due to consolidation.  A simple model would be
to have one thread malloc blocks and pass it on to another thread,
which then frees the block.  You could scale this to a number of
producers and consumers, either working in pairs or on a couple of
common pools.

Siddhesh
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