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Re: Enhancing malloc
- From: Siddhesh Poyarekar <siddhesh at redhat dot com>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: Will Newton <will dot newton at linaro dot org>, libc-alpha <libc-alpha at sourceware dot org>
- Date: Tue, 28 May 2013 18:24:44 +0530
- Subject: Re: Enhancing malloc
- References: <CANu=Dmj34hZoWr8A5dPThv14XUmP8vTgsxFLAbJ9jTTabRPqqA at mail dot gmail dot com> <20130528123317 dot GA17360 at domone dot kolej dot mff dot cuni dot cz>
On Tue, May 28, 2013 at 02:33:17PM +0200, OndÅej BÃlka wrote:
> Malloc and friends are one of few libc functions which can be measured
> directly. They account to about 50% of time spend in libc. I know that gcc
> hevavily uses malloc. So authoritative test could be if following is
> improvement or not:
>
> for I in `seq 1 10` do
> echo new
> LD_PRELOAD=new_malloc.so time gcc test.c
> echo old
> time gcc test.c
> done
>
> You must take into account that malloc requests are small. I did some
> measurements at
> http://kam.mff.cuni.cz/~ondra/benchmark_string/malloc_profile_28_11_2012.tar.bz2
For malloc and friends, the comparison should also include the effect
of the change on fragmentation (internal as well as external) and not
just speed of execution.
Siddhesh