Messages in this thread | ![/](/images/icornerl.gif) | | From | Yang Shi <> | Date | Thu, 20 Aug 2020 16:58:22 -0700 | Subject | Re: [RFC][PATCH 6/9] mm/vmscan: add page demotion counter |
| |
On Thu, Aug 20, 2020 at 3:26 PM Yang Shi <shy828301@gmail.com> wrote: > > On Tue, Aug 18, 2020 at 11:53 AM Dave Hansen > <dave.hansen@linux.intel.com> wrote: > > > > > > From: Yang Shi <yang.shi@linux.alibaba.com> > > > > 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.
I looks this problem has been fixed by commit 1a5bae25e3cf95c4e83a97f87a6b5280d9acbb22 ("mm/vmstat: add events for THP migration without split") in v5.9-rc1. With that commit, nr_succeeded will be bumped by 512 if a THP is migrated successfully (without split). So, we don't need worry about this anymore.
> > > > > Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> > > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> > > Cc: David Rientjes <rientjes@google.com> > > Cc: Huang Ying <ying.huang@intel.com> > > Cc: Dan Williams <dan.j.williams@intel.com> > > --- > > > > 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", > > _
| ![\](/images/icornerr.gif) |