[Mesa-dev] [RFC] ralloc: use jemalloc for faster GLSL compilation

[Michel Dänzer]

On 07/10/16 05:44 AM, Eric Anholt wrote:
> Marek Olšák <maraeo at gmail.com> writes:
> 
>> I'd like to have more feedback on the idea of using jemalloc for ralloc.
>>
>> Right now, I see these options:
>>
>> 1) Use jemalloc for ralloc and make it mandatory for all GL drivers.
>> - Distributions have shown that they are capable of doing anything
>> with the Mesa source code, so they don't need --disable-jemalloc.
>> - Reasonable people should build Mesa as-is.
>>
>> 2) Abandon the idea.
>> - The availability of --disable-jemalloc would send a clear message
>> that "you don't have to enable this", therefore the whole idea of
>> using jemalloc in Mesa would be pointless.
> 
> I'm generally of the opinion that if malloc is taking 10% of compile
> time, we're screwing up and we should just go fix that.  However, this
> is an easy fix and doesn't prevent going and fixing malloc abuse later.

I haven't seen anybody address the concern which was raised about having
multiple allocators independently grabbing heap from the kernel (and
possibly not returning it). Maybe it's not a big deal, but I'd like to
see at least a brief rationale as to why it's not. Marek, have you
compared the maximum heap usage with and without jemalloc, e.g. using
valgrind massif?


> I also don't like configure options -- they're mostly a chance to build
> things wrong.

I think you guys are over-dramatizing this a little. Most distros and
other users are probably using the defaults of most configure options,
so we just have to get the default right.


> I'm concerned that by shared linking against jemalloc we're going to run
> into similar problems to every other time we shared link against things
> and it's going to make our lives harder.  This is probably "we should
> figure out how to stop shared linking against anything" rather than "we
> shouldn't make this change", though.

Distros can't just link everything statically, if we try forcing that on
them they'll just have to revert the damage.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer