[Mesa-dev] [PATCH v2] glsls: Modify exec_list to avoid strict-aliasing violations

Francisco Jerez currojerez at riseup.net
Mon Jun 29 02:40:39 PDT 2015

Davin McCall <davmac at davmac.org> writes:

> On 26/06/15 14:53, Francisco Jerez wrote:
>> [...]
>> Your first approach seemed quite reasonable IMHO.  Were you able to
>> measure any performance regression from it?
>> Thanks.
> When I run an apitrace replay of a Dota 2 trace [1] with 
> LIBGL_ALWAYS_SOFTWARE and without the patch I get (averaged over 5 runs):
>      Maximum Resident Set Size (kbytes): 4509696
>      FPS: .9044752
>      user time: 2467.306
> ("Maximum Resident Set Size" and user time are given by GNU "time". I'm 
> not sure what it's really measuring, because this is a 32-bit system and 
> I don't see how the maximum resident set could be > 4GB; "top" shows 
> virt+res capping out at about 2.3GB. However I assume MRSS is at least 
> giving some relative indication of memory use; the deviation wasn't too 
> high).
> With the patch (again averaged over 5 runs):
>      Maximum Resident Set Size: 4523622.4
>      FPS: 0.9068524
>      user time: 2457.506
> So, "MRSS" has gone up a bit, but nothing else has changed 
> significantly. I think that means memory use has slightly increased, but 
> performance hasn't really changed.
> I wanted to test with the Intel driver using INTEL_NO_HW, but I get a 
> segfault when the patch is applied. Having checked over the patch 
> several times, I think this might mean that it triggers a latent bug 
> elsewhere, but I am still investigating that. V2 of the patch does not 
> trigger this crash.

Most likely some assumption left to fix in the i965 back-end?  Have you
shared your changes to the i965 driver already?  They don't seem to be
part of your v1.


> [1]  http://people.freedesktop.org/~anholt/dota_linux.trace
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