Re: [PATCH net-next v10 06/14] page_pool: convert to use netmem

[Pavel Begunkov]

On 6/6/24 02:48, Steven Rostedt wrote:
> On Thu, 30 May 2024 20:16:05 +0000
> Mina Almasry <almasrymina@xxxxxxxxxx> wrote:
>
> > @@ -42,51 +42,52 @@ TRACE_EVENT(page_pool_release,
> >   TRACE_EVENT(page_pool_state_release,
> >   
> >   	TP_PROTO(const struct page_pool *pool,
> > -		 const struct page *page, u32 release),
> > +		 netmem_ref netmem, u32 release),
> >   
> > -	TP_ARGS(pool, page, release),
> > +	TP_ARGS(pool, netmem, release),
> >   
> >   	TP_STRUCT__entry(
> >   		__field(const struct page_pool *,	pool)
> > -		__field(const struct page *,		page)
> > +		__field(netmem_ref,			netmem)
>
> Why make this of type "netmem_ref" and not just "unsigned long"?
>
> >   		__field(u32,				release)
> >   		__field(unsigned long,			pfn)
> >   	),
> >   
> >   	TP_fast_assign(
> >   		__entry->pool		= pool;
> > -		__entry->page		= page;
> > +		__entry->netmem		= netmem;
>
> You could have this be:
>
> 		__entry->netmem		= (__force unsigned long)netmem;
>
> >   		__entry->release	= release;
> > -		__entry->pfn		= page_to_pfn(page);
> > +		__entry->pfn		= netmem_to_pfn(netmem);
> >   	),
> >   
> > -	TP_printk("page_pool=%p page=%p pfn=0x%lx release=%u",
> > -		  __entry->pool, __entry->page, __entry->pfn, __entry->release)
> > +	TP_printk("page_pool=%p netmem=%lu pfn=0x%lx release=%u",
> > +		  __entry->pool, (__force unsigned long)__entry->netmem,
>
> And not have to expose the above text to user space (look at the format
> file it produces).
>
> It being of type "netmem_ref" in the ring buffer is useless.

netmem is a pointer with one bit serving as a flag, considering
mangling it might be better to %p it and perhaps also print its
type (page* vs iov) separately.

--
Pavel Begunkov