Hi Everyone,
A while back Alexandre Derumier posted some test results looking at how
transparent huge pages can reduce memory usage with jemalloc. I went
back and ran a number of new tests on the community performance cluster
to verify his findings and also look at how performance and cpu usage
were affected, both during various fio benchmark tests and also during a
4k random write recovery scenario. I tested tcmalloc 2.4 with 32MB
thread cache, 128MB thread cache, and jemalloc 4.0.
The gist of it is that I also see a reduction in memory usage, most
pronounced with jemalloc. Unfortuantely the best reduction in memory
usage is when memory usage is already fairly low. The most important
case is the memory spike when OSDs are marked back up/in during a
recovery test. In this case there is still a benefit, though memory
usage is still a little higher than TCMalloc with 128MB thread cache.
There's a little bit of a concerning trend where memory usage appears to
increase fairly quickly after the recovery test is complete and the
post-recovery phase of the benchmark is running. That will likely need
to be investigate in more depth.
I have been doing some other tests with the async messenger and
newstore, but those will have to wait for another paper.
Here's are the results:
https://drive.google.com/file/d/0B2gTBZrkrnpZY3U3TUU3RkJVeVk/view
Mark
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