Re: [PATCH v2 10/11] mm/vmstat: switch vmstat shepherd to flush per-CPU counters remotely

From: Peter Xu <peterx@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Christoph Lameter <cl@linux.com>,
	Aaron Tomlin <atomlin@atomlin.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2 10/11] mm/vmstat: switch vmstat shepherd to flush per-CPU counters remotely
Date: Thu, 2 Mar 2023 16:30:41 -0500	[thread overview]
Message-ID: <ZAEVge3W3bL+GNtx@x1n> (raw)
In-Reply-To: <ZAESOs/EeMCNp7YX@tpad>

On Thu, Mar 02, 2023 at 06:16:42PM -0300, Marcelo Tosatti wrote:
> On Thu, Mar 02, 2023 at 04:01:07PM -0500, Peter Xu wrote:
> > On Thu, Feb 09, 2023 at 12:02:00PM -0300, Marcelo Tosatti wrote:
> > > +#ifdef CONFIG_HAVE_CMPXCHG_LOCAL
> > > +/* Flush counters remotely if CPU uses cmpxchg to update its per-CPU counters */
> > > +static void vmstat_shepherd(struct work_struct *w)
> > > +{
> > > +	int cpu;
> > > +
> > > +	cpus_read_lock();
> > > +	for_each_online_cpu(cpu) {
> > > +		cpu_vm_stats_fold(cpu);
> > 
> > Nitpick: IIUC this line is the only change with CONFIG_HAVE_CMPXCHG_LOCAL
> > to replace the queuing.  Would it be cleaner to move the ifdef into
> > vmstat_shepherd, then, and keep the common logic?
> 
> https://lore.kernel.org/lkml/20221223144150.GA79369@lothringen/

:-)

[...]

> So it seems the current separation is quite readable
> (unless you have a suggestion).

No, feel free to ignore any of my nitpicks when you don't think proper. :)
Keeping it is fine to me.

-- 
Peter Xu