[sldev] [VWR] idle_mem_check()

Soft soft at lindenlab.com
Wed Jul 23 10:38:03 PDT 2008


On Wed, Jul 23, 2008 at 8:34 AM, Soft <soft at lindenlab.com> wrote:
> On Wed, Jul 23, 2008 at 7:32 AM, Robin Cornelius
> <robin.cornelius at gmail.com> wrote:
>>
>> Hey Everyone,
>>
>> Whist looking through the idle loop i came across the idle_mem_check()
>> function. What this does is every frame allocate 10MB of memory in 1MB
>> chunks then frees them again, just to check it can.
>>
>> This seems like a generally bad idea and if you are already hitting swap
>> space its going to contribute to a swap storm and lets face it, if you
>> can't allocate 10MB your pretty screwed anyway, something going to crash
>> or be terminated *very* soon.
>>
>> I would also imagine this can lead to memory fragmentation (although i
>> am blissfully unaware how well OS's cope with this these days).
>>
>> I did get a small increase in FPS by removing it. My viewer was at
>> 5.9-6.0 FPS in a sim with no avatars in or out (or moving) after
>> removing the idle_mem_check() i got 7.0 FPS in exactly the same location.
>>
>> I vote its removed but wanted to see if there are any comments or good
>> reasons why it needs to still be there.
>
> To my eye, it looks like some debug code that slipped into release,
> and I have mailed the Linden who added this to ask for more details.
> Note that it's also going to leak up to 9 megs plus the container when
> one of the 1 meg allocations fails, as it bails from the routine
> without doing cleanup on the first failure.

It's very late in the QA cycle for the 1.20 viewer, so it might ship
there. But it is gone from our release/ branch as will be reflected in
the next release/ drop. Thank you for pointing this out.


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