Re: [PATCH] drm/xe/bo: Cache vram_region_gpu_offset in struct xe_bo

[Yicong Hui <yiconghui@gmail.com>]

On 01/04/2026 04:52, Matthew Brost wrote:
> On Wed, Apr 01, 2026 at 02:53:17AM +0000, Yuri Martins wrote:
>> Hi Thomas,
>>
>> Thanks for the review and the detailed feedback on the move_notify pattern.
>>
>> You're right to ask for performance data, I don't have any. My hardware
>> (Core Ultra 7 258V) is integrated-only, so vram_region_gpu_offset() returns
>> 0 and the path this targets was never exercised. I should have realized
>> that before submitting.
> All good — we should probably just delete this XXX, as it was an early
> comment from me back when I still had the i915 micro-optimization
> mindset. I agree with Thomas that a change like this has little to no
> impact, given that binds (where this code is typically used) are orders
> of magnitude slower than clearing or moving memory. Plus, binds really
> only end up in the critical path during page faults — and even there,
> we’re usually moving memory first, so a little pointer chasing isn’t
> going to show up.
>
> As someone who has done quite a bit of perf work, here are the areas we
> should focus on cleaning up:
>
> - Time-complexity reduction (e.g., if we can go from O(N²) to O(N log N),
>    etc.)
> - Reduce unnecessary context switches (e.g., don’t call queue_work()
>    blindly when it has nothing to do)
> - Memory placement improvements (e.g., move CPU-read buffers to system
>    memory; move GPU-read buffers to VRAM)
> - Use the hardware correctly (e.g., reduce GPU context switches for
>    common kernel operations, etc.)
>
> Matt
>
>> Withdrawing this patch.
>>
>> Thanks,
>> Yuri
Hi Matthew,

I'm new to kernel development, and I was reading mailing list archives 
and was interested by your comment - I want to try exploring your 
suggestions for performance-improvement patches, particularly in 
reducing time complexity. Do you know of any areas of code within the xe 
drivers that I could potentially try to work on? My personal machine 
runs a Core Ultra processor.

Thank you for your time!
Yicong