[PATCH] drm/ttm: increase ttm pre-fault value to PMD size

[Zhu Lingshan]

Please ignore this patch, V2 will be send out soon

Thanks
Zhu Lingshan

On 5/30/2024 12:02 PM, Huang Rui wrote:
> On Thu, May 30, 2024 at 11:41:04AM +0800, Zhu, Lingshan wrote:
>> ttm page fault handler ttm_bo_vm_fault_reserved() maps
>> TTM_BO_VM_NUM_PREFAULT more pages beforehand
>> due to the principle of locality.
>>
>> However, on some platform the page faults are more costly, this
>> patch intends to increase the number of ttm pre-fault to relieve
>> the number of page faults.
>>
>> When multiple levels of page table is supported, the new default
>> value would be the PMD size, similar to huge page.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu at amd.com>
> Thanks Lingshan.
>
> I suggested to add reported-by from Jiangxiang like that:
>
> Reported-by: Jingxiang Li <jingxiang.li at ecarxgroup.com>
>
> Jingxiang, could you please test this patch? We expect to have a Tested-by. :-)
>
> Thanks,
> Ray
>
>> ---
>>  include/drm/ttm/ttm_bo.h | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
>> index 6ccf96c91f3a..c20ef44002da 100644
>> --- a/include/drm/ttm/ttm_bo.h
>> +++ b/include/drm/ttm/ttm_bo.h
>> @@ -39,7 +39,11 @@
>>  #include "ttm_device.h"
>>  
>>  /* Default number of pre-faulted pages in the TTM fault handler */
>> -#define TTM_BO_VM_NUM_PREFAULT 16
>> +#ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES
>> +#define TTM_BO_VM_NUM_PREFAULT (1 << (PMD_SHIFT - PAGE_SHIFT))
>> +#else
>> + #define TTM_BO_VM_NUM_PREFAULT 16
>> +#endif
>>  
>>  struct iosys_map;
>>  
>> -- 
>> 2.45.1
>>