FreeBSD 9.1 vs CentOS 6.3

[Adrian Chadd]

Hi,

I recall that there were significant issues with jemalloc on
computational loads, primarily because of the alignment jemalloc ends
up giving to various allocation sizes and the cache-busting behaviour
of that.

Does anyone remember the thread in which that happened? Maybe someone
posted a patch that lets people quickly tweak jemalloc to try and
avoid this?




Adrian


On 23 March 2013 13:34, Daniel Bilik <daniel.bilik at neosystem.cz> wrote:
> On Fri, 22 Mar 2013 10:03:27 +0100
> Davide D'Amico <davide.damico at contactlab.com> wrote:
>
>> Hi, I'm doing performance tests on a DELL R720, follows dmesg:
>> ...
>> I will use this server as a mysql-5.6 dbserver so I have a root
>> partition using a hw raid1 and a /DATAZFS partition, follows
>> configuration:
>> ...
>
> Well, it seems to be interesting coincidence... We've just finished
> benchmarking MySQL with various (m)allocators. The goal was to test
> tcmalloc, but when the system was up and running, we've taken the
> opportunity to benchmark also other alternatives... including jemalloc.
> All tests were performed on default MySQL 5.5.28 running on Debian Wheezy.
> Between the tests nothing was touched on the machine or the system, just
> allocators were changed (ie. mysqld restarted).
>
> Results for different test modes are available here...
>
> http://neosystem.cz/benchmark/mysql/
>
> It seems there is notable performance penalty for read-only transactions
> when MySQL is using jemalloc. The more concurrent threads are running, the
> more is jemalloc losing to other allocators. The penalty is also there for
> read-write transactions, but not that significant (error bars in the
> histograms also show that results for read-write tests tend to be very
> unstable). OTOH in non-transactional tests, jemalloc seems to be in par
> with others, and under specific load can even outperform some of them.
>
> In your original post, there is not mentioned in what mode you've performed
> OLTP test, but according to numbers I suspect it was "complex", ie.
> transactional. Can you repeat tests (both on CentOS and FreeBSD) with
> --oltp-test-mode=nontrx and/or simple?
>
> --
>                                                 Daniel Bilik
>                                                 neosystem.cz
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