Re: [PATCH] drm/xe/sa: Drop hardcoded 4K guard in sub-allocator

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 18.12.2024 10:15, Matthew Auld wrote:
> On 17/12/2024 22:39, Matthew Brost wrote:
>> On Tue, Dec 17, 2024 at 11:22:46PM +0100, Michal Wajdeczko wrote:
>>> Any required prefetch guards are added during batch buffer
>>> allocations anyway.
>>>
>>
>> This should work but I think we actually want to do the opposite of
>> this - drop the prefetch pad in BB allocation. This would enable a more
>> optimial usage of each suballocation. I think that would work unless we
>> have an odd caching issue - if caching is a problem then maybe the BB is
>> a cacheline.
> 
> Also would be good to update bb_prefetch(), since current prefetch value
> is too small for xe2+ on some engines, so the hardcoded 4K here was
> maybe saving the day.

since I don't what would be a good value for xe2+, I'll hold with this
patch until someone fixes the bb_prefetch()

> 
>>
>> I haven't had time to try to out yet but I think we explore the above
>> option first. If I'm missing something and the above does not work, then
>> agree with this patch.
>>
>> Matt
>>