| Message ID | 20241011103609.1992042-1-mengensun@tencent.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: make pcp decay work with onhz | expand |
On Fri, 11 Oct 2024 18:36:10 +0800 alexjlzheng@gmail.com wrote: > Subject: [PATCH] mm: make pcp decay work with onhz "NOHZ". > Date: Fri, 11 Oct 2024 18:36:10 +0800 > X-Mailer: git-send-email 2.39.3 > > From: MengEn Sun <mengensun@tencent.com> > > when a cpu stops tick, quiet_vmstat may flush all the per cpu > statistics counter. > > while, the shepherd is needed those counters to kick the > vmstat_work. > > when a cpu in nohz with a lot of pcp pages, and do not do page > allocating and freeing. the pcp pages of the cpu may not be hold > for a long time > > we make shepherd keep a eye on the pcp high_min and high_max I can see what you're saying here, but it's hard to understand. Please spend a little time clarifying the text? And please start sentences with a capital letter! > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -2024,8 +2024,13 @@ static bool need_update(int cpu) > > for_each_populated_zone(zone) { > struct per_cpu_zonestat *pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu); > + struct per_cpu_pages *pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu); > struct per_cpu_nodestat *n; > > + /* in onhz or nohz full make pcp decay work */ "NOHZ". > + if (pcp->high_max > pcp->high_min) > + return true; > + > /* > * The fast way of checking if there are any vmstat diffs. > */ > --
On Sat, 12 Oct 2024 15:43:28 -0700 akpm@linux-foundation.org wrote: > On Fri, 11 Oct 2024 18:36:10 +0800 alexjlzheng@gmail.com wrote: > > > Subject: [PATCH] mm: make pcp decay work with onhz > > "NOHZ". > > > Date: Fri, 11 Oct 2024 18:36:10 +0800 > > X-Mailer: git-send-email 2.39.3 > > > > From: MengEn Sun <mengensun@tencent.com> > > > > when a cpu stops tick, quiet_vmstat may flush all the per cpu > > statistics counter. > > > > while, the shepherd is needed those counters to kick the > > vmstat_work. > > > > when a cpu in nohz with a lot of pcp pages, and do not do page > > allocating and freeing. the pcp pages of the cpu may not be hold > > for a long time > > > > we make shepherd keep a eye on the pcp high_min and high_max > > I can see what you're saying here, but it's hard to understand. Please > spend a little time clarifying the text? And please start sentences > with a capital letter! Thank you for your suggestion I will create a v2 version, and make text clarifyed > > > --- a/mm/vmstat.c > > +++ b/mm/vmstat.c > > @@ -2024,8 +2024,13 @@ static bool need_update(int cpu) > > > > for_each_populated_zone(zone) { > > struct per_cpu_zonestat *pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu); > > + struct per_cpu_pages *pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu); > > struct per_cpu_nodestat *n; > > > > + /* in onhz or nohz full make pcp decay work */ > > "NOHZ". > > > + if (pcp->high_max > pcp->high_min) > > + return true; > > + > > /* > > * The fast way of checking if there are any vmstat diffs. > > */ > > --
diff --git a/mm/vmstat.c b/mm/vmstat.c index 1917c034c045..32768fb8f769 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -2024,8 +2024,13 @@ static bool need_update(int cpu) for_each_populated_zone(zone) { struct per_cpu_zonestat *pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu); + struct per_cpu_pages *pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu); struct per_cpu_nodestat *n; + /* in onhz or nohz full make pcp decay work */ + if (pcp->high_max > pcp->high_min) + return true; + /* * The fast way of checking if there are any vmstat diffs. */