talloc vs malloc speed

[Andrew Walker]

I was playing around with building talloc with jemalloc not too long
ago https://github.com/truenas/samba/pull/241/commits/2476bfd3012a95e8015e2b61d3475d6f8cf11476
Some thoughts:
1) there was some benefit to removing the memlimit API. Might be worth
a shot retesting with it ripped out at different optimizations levels.
2) there was also some benefit for case of talloc_zero() if we called
directly into calloc() rather than doing malloc() followed by
memset().

Andrew

On Fri, Apr 14, 2023 at 1:12 PM Andreas Schneider via samba-technical
<samba-technical at lists.samba.org> wrote:
>
> Hi,
>
> Florian Weimer implemented hwcaps support in glibc. This allows you to drop
> optimized libraries.
>
> The support for this is enabled in openSUSE Tumbleweed right now [1]. I've
> enabled it for libtalloc as you want to to be as fast as possible.
>
>
> Here are the results from my AMD Ryzen 9 3900X 12-Core processor.
>
> talloc x86_64_v1 (testsuite compiled with -O0)
>
> test: speed
> # TALLOC VS MALLOC SPEED
> talloc:       46623469 ops/sec
> talloc_pool:  74121933 ops/sec
> malloc:       66443400 ops/sec
> success: speed
>
> => talloc is 30% slower
>
>
>
> talloc x86_64_v3 (testsuite compiled with -O0)
>
> test: speed
> # TALLOC VS MALLOC SPEED
> talloc:       47783809 ops/sec
> talloc_pool:  75068595 ops/sec
> malloc:       68073710 ops/sec
> success: speed
>
> => talloc is 30% slower
>
>
>
> talloc x86_64_v3 (testsuite compiled with -O2)
> test: speed
> # TALLOC VS MALLOC SPEED
> talloc:       50633005 ops/sec
> talloc_pool:  74245533 ops/sec
> malloc:      219259200 ops/sec
> success: speed
>
> => talloc is 77% slower
>
>
> It looks like the optimizer is able to optimize the code a lot more if malloc
> is used.
>
> I wonder if it would be possible to give the optimizer more hints. Maybe
> Florian has some ideas :-)
>
>
> Best regards
>
>
>         Andreas
>
>
> P.S. The talloc website states it is 4% slower than malloc. This was probably
> a long long time ago ;-)
>
>
> [1] https://www.phoronix.com/news/glibc-hwcaps-RFC
> [2] https://news.opensuse.org/2023/03/02/tw-gains-optional-optimizations/
>
> --
> Andreas Schneider                      asn at samba.org
> Samba Team                             www.samba.org
> GPG-ID:     8DFF53E18F2ABC8D8F3C92237EE0FC4DCC014E3D
>
>
>