Re: [RFC PATCH 2/2] mm: add zero_user_folio_segments()

["Yin, Fengwei" <fengwei.yin@intel.com>]

On 2/17/2023 3:19 AM, Matthew Wilcox wrote:
> On Fri, Feb 17, 2023 at 12:05:28AM +0800, Yin Fengwei wrote:
>> zero_user_folio_segments() has same function as zero_user_segments().
>> but take folio as parameter. Update folio_zero_segments(),
>> folio_zero_segment() and folio_zero_range() to use it.
> 
> If we were going to do something like this, then it should be
> folio_zero_segments(), not zero_user_folio_segments().
> 
> But I don't understand the advantage to adding this right now.
> We're adding a new function that does exactly the same thing
> as zero_user_segments() for no real benefit that I can see.
> 
> My plan was always to eventually kill off zero_user_segment()
> zero_user_segments() and zero_user(), and then move the
> implementation of zero_user_segments() to be the implementation
> of folio_zero_segments().  But we still have ~100 calls to
> those three functions, so we can't do that yet.
> 
> 
> If you're looking for something to do, how about batching calls to
> page_remove_rmap() in try_to_unmap_one()?  That's a pretty hairy
> function, but I think that you'll see similar gains to the ones
> you saw with page_add_file_rmap() since it's manipulating the
> same counters.
Yes. I am trying to make some change base on folio to get to know
about folio's API. Thanks a lot for the suggestion and I will check
how to batched page_remove_rmap() in try_to_unmap_one().


Regards
Yin, Fengwei