Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Per-process page size

[Askar Safin]

Jan Kara <jack@xxxxxxx>:
> > Is there some other way for someone to block a page from getting evicted
> > from the pagecache?
> > 
> > We have this memfd_pin_folios() thing, but I don't think we have something
> > comparable for ordinary pagecache files.
> > 
> > ... putting them into a pipe and never reading from the pipe maybe (I assume
> > that's what splice() does, but not sure if it actually places the pages in
> > there or whether it creates a copy first)?
> 
> Standard splice copies data first (it's using standard IO callbacks such as
> ->read_iter) so that doesn't pin page cache AFAICT. Only vmsplice(2) does
> but that requires mmap.

Splice from page cache to pipe sometimes doesn't copy data.

That is why test program mentioned here may print "new":
https://lore.kernel.org/all/CAHk-=wjixHw6n_R5TQWW1r0a+GgFAPGw21KMj6obkzr3qXXbYA@xxxxxxxxxxxxxx/

-- 
Askar Safin