[Sheepdog] [PATCH] use tcmalloc if it is available

[MORITA Kazutaka]

At Wed, 16 Nov 2011 02:59:21 -0500,
Christoph Hellwig wrote:
> 
> Di you run any benchmarks and/or look at memory use with an without
> tcmalloc?  It worked great where I used it, but I really like to have
> numers for changes like this.

I've run the following benchmark on VM:

  for bs in 4 16 64 256 1024; do
      dd if=/dev/zero of=/dev/sdb bs=${bs}k oflag=direct count=1024
  done

Sheepdog is started with one node and running on ext3 (barrier=1).

The result are as follows:

bs      with tcmalloc  without tcmalloc
---------------------------------------
  4 KB       488 kB/s          487 kB/s
 16 KB       1.9 MB/s          1.9 MB/s
 64 KB       7.2 MB/s          7.1 MB/s
256 KB      22.4 MB/s         22.3 MB/s
  1 MB      34.4 MB/s         34.4 MB/s


There were no obvious difference between them, so for now I think of
dropping the tcmalloc patch.  Let me know if anyone got different
results.

Thanks,

Kazutaka