Re: [Mesa-dev] [PATCH 2/2] anv: Use build-id for pipeline cache UUID.

[Kenneth Graunke]

On Tuesday, February 14, 2017 12:38:45 PM PST Chad Versace wrote:
> On Tue 14 Feb 2017, Matt Turner wrote:
> 
> 
> >  static bool
> > -anv_get_function_timestamp(void *ptr, uint32_t* timestamp)
> > +anv_device_get_cache_uuid(void *uuid)
> >  {
> > -   Dl_info info;
> > -   struct stat st;
> > -   if (!dladdr(ptr, &info) || !info.dli_fname)
> > +   const struct note *note = build_id_find_nhdr("libvulkan_intel.so");
> > +   if (!note)
> >        return false;
> >  
> > -   if (stat(info.dli_fname, &st))
> > +   unsigned len = build_id_length(note);
> > +   if (len < VK_UUID_SIZE)
> >        return false;
> >  
> > -   *timestamp = st.st_mtim.tv_sec;
> > -   return true;
> > -}
> > -
> > -static bool
> > -anv_device_get_cache_uuid(void *uuid)
> > -{
> > -   uint32_t timestamp;
> > -
> > -   memset(uuid, 0, VK_UUID_SIZE);
> > -   if (!anv_get_function_timestamp(anv_device_get_cache_uuid, &timestamp))
> > +   unsigned char *build_id = malloc(len);
> > +   if (!build_id)
> >        return false;
> >  
> > -   snprintf(uuid, VK_UUID_SIZE, "anv-%d", timestamp);
> > +   build_id_read(note, build_id);
> > +
> > +   memcpy(uuid, build_id, VK_UUID_SIZE);
> > +   free(build_id);
> 
> The Vulkan spec frowns on memory allocations when not needed. If you
> must allocate memory here, then it should be through the VkInstance
> allocation callbacks. However, it's best to avoid the allocation by
> adding a size_t parameter, à la snprintf, to build_id_read().
> 
> Otherwise, the patch looks good to me.

You're worried about the performance of anv_physical_device_init()?
This doesn't happen on lookup...just driver start up...

--Ken

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