On Tue, Aug 18, 2020 at 11:53 AM Dave Hansen <[email protected]> wrote: > > > From: Yang Shi <[email protected]> > > Account the number of demoted pages into reclaim_state->nr_demoted. > > Add pgdemote_kswapd and pgdemote_direct VM counters showed in > /proc/vmstat. > > [ daveh: > - __count_vm_events() a bit, and made them look at the THP > size directly rather than getting data from migrate_pages() > ]
This reminds me that we'd better to make migrate_pages() return the number of base pages. Now both nr_failed and nr_succeeded is inc'ed regardless of whether it is THP. A quick look finds the callers of migrate_pages() seem not care about the exact returned number, they just care if it is positive or not. And reclaim code depends on correct nr_succeeded to avoid over reclaim. I will come up with a patch to post to the mailing list. > > Signed-off-by: Yang Shi <[email protected]> > Signed-off-by: Dave Hansen <[email protected]> > Cc: David Rientjes <[email protected]> > Cc: Huang Ying <[email protected]> > Cc: Dan Williams <[email protected]> > --- > > b/include/linux/vm_event_item.h | 2 ++ > b/mm/vmscan.c | 6 ++++++ > b/mm/vmstat.c | 2 ++ > 3 files changed, 10 insertions(+) > > diff -puN include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter > include/linux/vm_event_item.h > --- a/include/linux/vm_event_item.h~mm-vmscan-add-page-demotion-counter > 2020-08-18 11:36:54.062583176 -0700 > +++ b/include/linux/vm_event_item.h 2020-08-18 11:36:54.070583176 -0700 > @@ -32,6 +32,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS > PGREFILL, > PGSTEAL_KSWAPD, > PGSTEAL_DIRECT, > + PGDEMOTE_KSWAPD, > + PGDEMOTE_DIRECT, > PGSCAN_KSWAPD, > PGSCAN_DIRECT, > PGSCAN_DIRECT_THROTTLE, > diff -puN mm/vmscan.c~mm-vmscan-add-page-demotion-counter mm/vmscan.c > --- a/mm/vmscan.c~mm-vmscan-add-page-demotion-counter 2020-08-18 > 11:36:54.064583176 -0700 > +++ b/mm/vmscan.c 2020-08-18 11:36:54.072583176 -0700 > @@ -147,6 +147,7 @@ struct scan_control { > unsigned int immediate; > unsigned int file_taken; > unsigned int taken; > + unsigned int demoted; > } nr; > > /* for recording the reclaimed slab by now */ > @@ -1146,6 +1147,11 @@ static unsigned int demote_page_list(str > list_splice(ret_list, demote_pages); > } > > + if (current_is_kswapd()) > + __count_vm_events(PGDEMOTE_KSWAPD, nr_succeeded); > + else > + __count_vm_events(PGDEMOTE_DIRECT, nr_succeeded); > + > return nr_succeeded; > } > > diff -puN mm/vmstat.c~mm-vmscan-add-page-demotion-counter mm/vmstat.c > --- a/mm/vmstat.c~mm-vmscan-add-page-demotion-counter 2020-08-18 > 11:36:54.067583176 -0700 > +++ b/mm/vmstat.c 2020-08-18 11:36:54.072583176 -0700 > @@ -1200,6 +1200,8 @@ const char * const vmstat_text[] = { > "pgrefill", > "pgsteal_kswapd", > "pgsteal_direct", > + "pgdemote_kswapd", > + "pgdemote_direct", > "pgscan_kswapd", > "pgscan_direct", > "pgscan_direct_throttle", > _
