Re: [PATCH net-next] page_pool: Rename frag_users to frag_cnt

[Ilias Apalodimas]

Hi Yunsheng,

On Thu, 21 Dec 2023 at 04:07, Yunsheng Lin <linyunsheng@xxxxxxxxxx> wrote:
>
> On 2023/12/20 15:56, Ilias Apalodimas wrote:
> > Hi Yunsheng,
> >>>>>  #ifdef CONFIG_PAGE_POOL_STATS
> >>>>>       /* these stats are incremented while in softirq context */
> >>>>> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> >>>>> index 9b203d8660e4..19a56a52ac8f 100644
> >>>>> --- a/net/core/page_pool.c
> >>>>> +++ b/net/core/page_pool.c
> >>>>> @@ -659,7 +659,7 @@ EXPORT_SYMBOL(page_pool_put_page_bulk);
> >>>>>  static struct page *page_pool_drain_frag(struct page_pool *pool,
> >>>>>                                        struct page *page)
> >>>>>  {
> >>>>> -     long drain_count = BIAS_MAX - pool->frag_users;
> >>>>> +     long drain_count = BIAS_MAX - pool->frag_cnt;
> >>>>
> >>>> drain_count = pool->refcnt_bais;
> >>>
> >>> I think this is a typo right? This still remains
> >>
> >> It would be better to invert logic too, as it is mirroring:
> >>
> >> https://elixir.bootlin.com/linux/v6.7-rc5/source/mm/page_alloc.c#L4745
> >
> > This is still a bit confusing for me since the actual bias is the
> > number of fragments that you initially split the page. But I am fine
> Acctually there are two bais numbers for a page used by
> page_pool_alloc_frag().
> the one for page->pp_ref_count, which already use the BIAS_MAX, which
> indicates the initial bais number:
> https://elixir.bootlin.com/linux/latest/source/net/core/page_pool.c#L779
>
> Another one for pool->frag_users indicating the runtime bais number, which
> need changing when a page is split into more fragments:
> https://elixir.bootlin.com/linux/latest/source/net/core/page_pool.c#L776
> https://elixir.bootlin.com/linux/latest/source/net/core/page_pool.c#L783

I know, and that's exactly what my commit message explains.  Also,
that's the reason that the rename was 'frag_cnt' on v1.

/Ilias
>
> > with having a common approach. I'll send the rename again shortly, and
> > I can send the logic invert a bit later (or feel free to send it,
> > since it was your idea).
> >
> > Thanks
> > /Ilias
> > .
> >