Re: [PATCH rfc 4/4] mm: filemap: try to batch lruvec stat updating

[Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>]

On 2024/5/9 22:01, Johannes Weiner wrote:
> On Tue, May 07, 2024 at 05:06:57PM +0800, Kefeng Wang wrote:
> > > +static void filemap_lruvec_stat_update(struct mem_cgroup *memcg,
> > > +				       pg_data_t *pgdat, int nr)
> > > +{
> > > +	struct lruvec *lruvec;
> > > +
> > > +	if (!memcg) {
> > > +		__mod_node_page_state(pgdat, NR_FILE_MAPPED, nr);
> > > +		return;
> > > +	}
> > > +
> > > +	lruvec = mem_cgroup_lruvec(memcg, pgdat);
> > > +	__mod_lruvec_state(lruvec, NR_FILE_MAPPED, nr);
> > > +}
> > > +
> > >    vm_fault_t filemap_map_pages(struct vm_fault *vmf,
> > >    			     pgoff_t start_pgoff, pgoff_t end_pgoff)
> > >    {
> > > @@ -3628,6 +3642,9 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
> > >    	vm_fault_t ret = 0;
> > >    	unsigned long rss = 0;
> > >    	unsigned int nr_pages = 0, mmap_miss = 0, mmap_miss_saved, folio_type;
> > > +	struct mem_cgroup *memcg, *memcg_cur;
> > > +	pg_data_t *pgdat, *pgdat_cur;
> > > +	int nr_mapped = 0;
> > >    
> > >    	rcu_read_lock();
> > >    	folio = next_uptodate_folio(&xas, mapping, end_pgoff);
> > > @@ -3648,9 +3665,20 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
> > >    	}
> > >    
> > >    	folio_type = mm_counter_file(folio);
> > > +	memcg = folio_memcg(folio);
> > > +	pgdat = folio_pgdat(folio);
>
> You should be able to do:
>
> 	lruvec = folio_lruvec(folio);
>
> and then pass that directly to filemap_lruvec_stat_update().

It's obviously better, will update and address David's comment in 
patch3, thank you.