From: Christoph Lameter <cl@gentwo.de>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: linux-kernel@vger.kernel.org, Nitesh Lal <nilal@redhat.com>,
Nicolas Saenz Julienne <nsaenzju@redhat.com>,
Frederic Weisbecker <frederic@kernel.org>,
Juri Lelli <juri.lelli@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Alex Belits <abelits@belits.com>, Peter Xu <peterx@redhat.com>
Subject: Re: [patch V3 8/8] mm: vmstat_refresh: avoid queueing work item if cpu stats are clean
Date: Wed, 25 Aug 2021 11:30:43 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2108251121260.317297@gentwo.de> (raw)
In-Reply-To: <20210824152646.948424573@fuller.cnet>
On Tue, 24 Aug 2021, Marcelo Tosatti wrote:
> 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.
The issue in the past was whether the effort to check is adding overhead
that is comparable to run refresh_vm_stats. YMMV.
> This fixes sosreport hang (which uses vmstat_refresh) with
> spinning SCHED_FIFO process.
Ughhh.. SCHED_FIFO is evil....
> #ifdef CONFIG_PROC_FS
> +static bool need_drain_remote_zones(int cpu)
Well this is not related to vm stats but per cpu pages of the page
allocator. Maybe call this need_drain_remote_pcp or something?
> @@ -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);
Do malloc instead? Using the percpu allocator frequently in a function to
allocator temporary variables can cause needless fragmentation there. The
percpu allocator does not have the frag management features of the slab
allocators.
next prev parent reply other threads:[~2021-08-25 9:40 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 ` [patch V3 8/8] mm: vmstat_refresh: avoid queueing work item if cpu stats are clean Marcelo Tosatti
2021-08-25 9:30 ` Christoph Lameter [this message]
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
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