From: Marcelo Tosatti <mtosatti@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Nitesh Lal <nilal@redhat.com>,
Nicolas Saenz Julienne <nsaenzju@redhat.com>,
Frederic Weisbecker <frederic@kernel.org>,
Christoph Lameter <cl@linux.com>,
Juri Lelli <juri.lelli@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Alex Belits <abelits@belits.com>, Peter Xu <peterx@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>
Subject: [patch V3 8/8] mm: vmstat_refresh: avoid queueing work item if cpu stats are clean
Date: Tue, 24 Aug 2021 12:24:31 -0300 [thread overview]
Message-ID: <20210824152646.948424573@fuller.cnet> (raw)
In-Reply-To: 20210824152423.300346181@fuller.cnet
It is not necessary to queue work item to run refresh_vm_stats
on a remote CPU if that CPU has no dirty stats and no per-CPU
allocations for remote nodes.
This fixes sosreport hang (which uses vmstat_refresh) with
spinning SCHED_FIFO process.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
mm/vmstat.c | 49 ++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 44 insertions(+), 5 deletions(-)
Index: linux-2.6/mm/vmstat.c
===================================================================
--- linux-2.6.orig/mm/vmstat.c
+++ linux-2.6/mm/vmstat.c
@@ -1851,6 +1851,31 @@ static bool need_update(int cpu)
}
#ifdef CONFIG_PROC_FS
+static bool need_drain_remote_zones(int cpu)
+{
+#ifdef CONFIG_NUMA
+ struct zone *zone;
+
+ for_each_populated_zone(zone) {
+ struct per_cpu_pages *pcp;
+
+ pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
+ if (!pcp->count)
+ continue;
+
+ if (!pcp->expire)
+ continue;
+
+ if (zone_to_nid(zone) == cpu_to_node(cpu))
+ continue;
+
+ return true;
+ }
+#endif
+
+ return false;
+}
+
static void refresh_vm_stats(struct work_struct *work)
{
refresh_cpu_vm_stats(true);
@@ -1860,8 +1885,12 @@ int vmstat_refresh(struct ctl_table *tab
void *buffer, size_t *lenp, loff_t *ppos)
{
long val;
- int err;
- int i;
+ int i, cpu;
+ struct work_struct __percpu *works;
+
+ works = alloc_percpu(struct work_struct);
+ if (!works)
+ return -ENOMEM;
/*
* The regular update, every sysctl_stat_interval, may come later
@@ -1875,9 +1904,19 @@ int vmstat_refresh(struct ctl_table *tab
* transiently negative values, report an error here if any of
* the stats is negative, so we know to go looking for imbalance.
*/
- err = schedule_on_each_cpu(refresh_vm_stats);
- if (err)
- return err;
+ get_online_cpus();
+ for_each_online_cpu(cpu) {
+ struct work_struct *work = per_cpu_ptr(works, cpu);
+
+ INIT_WORK(work, refresh_vm_stats);
+ if (need_update(cpu) || need_drain_remote_zones(cpu))
+ schedule_work_on(cpu, work);
+ }
+ for_each_online_cpu(cpu)
+ flush_work(per_cpu_ptr(works, cpu));
+ put_online_cpus();
+ free_percpu(works);
+
for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
/*
* Skip checking stats known to go negative occasionally.
next prev parent reply other threads:[~2021-08-24 15:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 15:24 [patch V3 0/8] extensible prctl task isolation interface and vmstat sync Marcelo Tosatti
2021-08-24 15:24 ` [patch V3 1/8] add basic task isolation prctl interface Marcelo Tosatti
2021-08-24 15:24 ` [patch V3 2/8] add prctl task isolation prctl docs and samples Marcelo Tosatti
2021-08-26 9:59 ` Frederic Weisbecker
2021-08-26 12:11 ` Marcelo Tosatti
2021-08-26 19:15 ` Christoph Lameter
2021-08-26 20:37 ` Marcelo Tosatti
2021-08-27 13:08 ` Frederic Weisbecker
2021-08-27 14:44 ` Marcelo Tosatti
2021-08-30 11:38 ` Frederic Weisbecker
2021-09-01 13:11 ` Nitesh Lal
2021-09-01 17:34 ` Marcelo Tosatti
2021-09-01 17:49 ` Nitesh Lal
2021-08-24 15:24 ` [patch V3 3/8] task isolation: sync vmstats on return to userspace Marcelo Tosatti
2021-09-10 13:49 ` nsaenzju
2021-08-24 15:24 ` [patch V3 4/8] procfs: add per-pid task isolation state Marcelo Tosatti
2021-08-24 15:24 ` [patch V3 5/8] task isolation: sync vmstats conditional on changes Marcelo Tosatti
2021-08-25 9:46 ` Christoph Lameter
2021-08-24 15:24 ` [patch V3 6/8] KVM: x86: call isolation prepare from VM-entry code path Marcelo Tosatti
2021-08-24 15:24 ` [patch V3 7/8] mm: vmstat: move need_update Marcelo Tosatti
2021-08-24 15:24 ` Marcelo Tosatti [this message]
2021-08-25 9:30 ` [patch V3 8/8] mm: vmstat_refresh: avoid queueing work item if cpu stats are clean Christoph Lameter
2021-09-01 13:05 ` Nitesh Lal
2021-09-01 17:32 ` Marcelo Tosatti
2021-09-01 18:33 ` Marcelo Tosatti
2021-09-03 17:38 ` Nitesh Lal
2021-08-25 10:02 ` [patch V3 0/8] extensible prctl task isolation interface and vmstat sync Marcelo Tosatti
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210824152646.948424573@fuller.cnet \
--to=mtosatti@redhat.com \
--cc=abelits@belits.com \
--cc=cl@linux.com \
--cc=frederic@kernel.org \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=nilal@redhat.com \
--cc=nsaenzju@redhat.com \
--cc=peterx@redhat.com \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).