[Beignet] [PATCH] driver/runtime: get global mem size dynamically

[Zhigang Gong]

On Fri, Oct 09, 2015 at 03:56:11PM +0800, Pan Xiuli wrote:
> The gen8 and higher gpu can have more than 2G mem, so we dynamically
> get the global mem size.
> 
> Signed-off-by: Pan Xiuli <xiuli.pan at intel.com>
> ---
>  src/cl_device_id.c       | 6 +++---
>  src/intel/intel_driver.c | 6 ++++++
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/src/cl_device_id.c b/src/cl_device_id.c
> index 78d2cf4..c3bd35f 100644
> --- a/src/cl_device_id.c
> +++ b/src/cl_device_id.c
> @@ -550,10 +550,10 @@ skl_gt4_break:
>  
>    struct sysinfo info;
>    if (sysinfo(&info) == 0) {
> -    uint64_t two_gb = 2 * 1024 * 1024 * 1024ul; 
> +    uint64_t totalgpumem = ret->global_mem_size;
>      uint64_t totalram = info.totalram * info.mem_unit;
> -    ret->global_mem_size = (totalram > two_gb) ? 
> -                            two_gb : info.totalram;
> +    ret->global_mem_size = (totalram > totalgpumem) ?
> +                            totalgpumem: totalram;
>      ret->max_mem_alloc_size = ret->global_mem_size / 2;

The "/ 2" is a hard coded method to avoid allocate too much memory
which is not supported by the platform. Now this patch changes to
get aperture size from libdrm, then we don't need to use it any more.

But we may still want to make sure that we don't allocate too much
system memory. I think totalram/2 should be a reasonable threshold value.

So the following code may be better:

reg->global_mem_size = min(totalram/2, totalgpumem);
reg->max_mem_alloc_size = min(global_mem_size/2, totalgpumem);

Furthermore we still need to check carefully whether it's safe to use
totalgpumem as the global_mem_size and/or max_mem_alloc_size.

If the test case tests the maximum memory size, and there are some aperture
space already allocated by system, then the case may be failed. Before submit
the patch, it's better to test it with all the related conformance test cases
on all platforms. Or maybe we need to add some cases to test edge conditions
into the internal unit test cases.

Thanks,
Zhigang Gong.

>    }
>  
> diff --git a/src/intel/intel_driver.c b/src/intel/intel_driver.c
> index 035a103..1f286f7 100644
> --- a/src/intel/intel_driver.c
> +++ b/src/intel/intel_driver.c
> @@ -829,6 +829,12 @@ intel_update_device_info(cl_device_id device)
>    if (IS_CHERRYVIEW(device->device_id))
>      printf(CHV_CONFIG_WARNING);
>  #endif
> +  //We should get the device memory dynamically, also the
> +  //mapablce mem size usage is unknown. Still use global_mem_size/2
> +  //as max_mem_alloc_size in cl_get_gt_device.
> +  size_t total_mem,map_mem;
> +  drm_intel_get_aperture_sizes(driver->fd,&map_mem,&total_mem);
> +  device->global_mem_size = (cl_ulong)total_mem;
>  
>    intel_driver_context_destroy(driver);
>    intel_driver_close(driver);
> -- 
> 2.1.4
> 
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