Re: [PATCH v3 0/4] mm: add more kernel parameters to control mTHP

["Maíra Canal" <mcanal@igalia.com>]

Hi Andrew,

On 30/10/24 19:50, Andrew Morton wrote:
> On Wed, 30 Oct 2024 09:58:54 -0300 Maíra Canal <mcanal@igalia.com> wrote:
> 
>> The second and third patches focus on controlling THP support for shmem
>> via the kernel command line. The second patch introduces a parameter to
>> control the global default huge page allocation policy for the internal
>> shmem mount.
> 
> The changelogs for patches 2 and 3 both say
> 
> : By configuring ..., applications that use shmem, such as the DRM GEM objects,
> : can take advantage of mTHP before it's been configured through sysfs.
> 
> There isn't a lot of info here - please explain this timing issue in
> more detail.
> 
> Because the question which leaps to mind is: shouldn't the
> "applications that use shmem" be changed to "configure mTHP through
> sysfs" *before* "using shmem"?  Seems pretty basic.

Sorry about that, I'll try to improve the commit messages and add more 
details.

As mentioned in the example I gave ("DRM GEM objects"), my main use is
GEM objects backed by shmem. I'd like to use Huge Pages on the GPU and I
can only do that if I have contiguous memory to back my objects.

I can't think how I can change sysfs from a DRM driver.

Best Regards,
- Maíra

> 
> 
> Also, please consider my question to be a critique of the changelogs.
> If the changelogs were complete, I wouldn't need to ask any questions!