From: Andrew Morton <akpm@linux-foundation.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, Kemi Wang <kemi.wang@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Michal Hocko <mhocko@suse.com>,
Mel Gorman <mgorman@techsingularity.net>,
Johannes Weiner <hannes@cmpxchg.org>,
Christopher Lameter <cl@linux.com>,
YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Nikolay Borisov <nborisov@suse.com>,
Pavel Tatashin <pasha.tatashin@oracle.com>,
David Rientjes <rientjes@google.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Dave <dave.hansen@linux.intel.com>,
Andi Kleen <andi.kleen@intel.com>,
Tim Chen <tim.c.chen@intel.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Ying Huang <ying.huang@intel.com>, Aaron Lu <aaron.lu@intel.com>,
Aubrey Li <aubrey.li@intel.com>, Linux MM <linux-mm@kvack.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm: NUMA stats code cleanup and enhancement
Date: Tue, 28 Nov 2017 13:56:53 -0800 [thread overview]
Message-ID: <20171128135653.608f4350f4245a633823f5e9@linux-foundation.org> (raw)
In-Reply-To: <87o9nmjlfv.fsf@linux.intel.com>
On Tue, 28 Nov 2017 10:40:52 -0800 Andi Kleen <ak@linux.intel.com> wrote:
> Vlastimil Babka <vbabka@suse.cz> writes:
> >
> > I'm worried about the "for_each_possible..." approach here and elsewhere
> > in the patch as it can be rather excessive compared to the online number
> > of cpus (we've seen BIOSes report large numbers of possible CPU's). IIRC
>
> Even if they report a few hundred extra reading some more shared cache lines
> is very cheap. The prefetcher usually quickly figures out such a pattern
> and reads it all in parallel.
>
> I doubt it will be noticeable, especially not in a slow path
> like reading something from proc/sys.
We say that, then a few years it comes back and bites us on our
trailing edges.
> > the general approach with vmstat is to query just online cpu's / nodes,
> > and if they go offline, transfer their accumulated stats to some other
> > "victim"?
>
> That's very complicated, and unlikely to be worth it.
for_each_online_cpu() and a few-line hotplug handler? I'd like to see
an implementation before deciding that it's too complex...
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-11-28 21:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-28 6:00 [PATCH 1/2] mm: NUMA stats code cleanup and enhancement Kemi Wang
2017-11-28 6:00 ` [PATCH 2/2] mm: Rename zone_statistics() to numa_statistics() Kemi Wang
2017-11-28 8:09 ` [PATCH 1/2] mm: NUMA stats code cleanup and enhancement Vlastimil Babka
2017-11-28 8:33 ` kemi
2017-11-28 18:40 ` Andi Kleen
2017-11-28 21:56 ` Andrew Morton [this message]
2017-11-28 22:52 ` Vlastimil Babka
2017-11-29 12:17 ` Michal Hocko
2017-11-30 5:56 ` kemi
2017-11-30 8:53 ` Michal Hocko
2017-11-30 9:32 ` kemi
2017-11-30 9:45 ` Michal Hocko
2017-11-30 11:06 ` Wang, Kemi
2017-12-08 8:38 ` kemi
2017-12-08 8:47 ` Michal Hocko
2017-12-12 2:05 ` kemi
2017-12-12 8:11 ` Michal Hocko
2017-12-14 1:40 ` kemi
2017-12-14 7:29 ` Michal Hocko
2017-12-14 8:55 ` kemi
2017-12-14 9:23 ` Michal Hocko
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=20171128135653.608f4350f4245a633823f5e9@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=aaron.lu@intel.com \
--cc=ak@linux.intel.com \
--cc=andi.kleen@intel.com \
--cc=aryabinin@virtuozzo.com \
--cc=aubrey.li@intel.com \
--cc=bigeasy@linutronix.de \
--cc=brouer@redhat.com \
--cc=cl@linux.com \
--cc=dave.hansen@linux.intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=hannes@cmpxchg.org \
--cc=kemi.wang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@suse.com \
--cc=nborisov@suse.com \
--cc=pasha.tatashin@oracle.com \
--cc=rientjes@google.com \
--cc=tim.c.chen@intel.com \
--cc=vbabka@suse.cz \
--cc=yasu.isimatu@gmail.com \
--cc=ying.huang@intel.com \
/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).