From: Chen Yu <yu.c.chen@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, Michal Hocko <mhocko@kernel.org>,
Mel Gorman <mgorman@techsingularity.net>,
Vlastimil Babka <vbabka@suse.cz>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] PM / Hibernate: Feed the wathdog when creating snapshot
Date: Tue, 22 Aug 2017 10:55:57 +0800 [thread overview]
Message-ID: <20170822025557.GA11870@yu-desktop-1.sh.intel.com> (raw)
In-Reply-To: <20170821132600.c8a509bcacce123e3f51d989@linux-foundation.org>
Hi Andrew,
On Mon, Aug 21, 2017 at 01:26:00PM -0700, Andrew Morton wrote:
> On Mon, 21 Aug 2017 23:08:18 +0800 Chen Yu <yu.c.chen@intel.com> wrote:
>
> > There is a problem that when counting the pages for creating
> > the hibernation snapshot will take significant amount of
> > time, especially on system with large memory. Since the counting
> > job is performed with irq disabled, this might lead to NMI lockup.
> > The following warning were found on a system with 1.5TB DRAM:
> >
> > ...
> >
> > It has taken nearly 20 seconds(2.10GHz CPU) thus the NMI lockup
> > was triggered. In case the timeout of the NMI watch dog has been
> > set to 1 second, a safe interval should be 6590003/20 = 320k pages
> > in theory. However there might also be some platforms running at a
> > lower frequency, so feed the watchdog every 100k pages.
> >
> > ...
> >
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -2531,9 +2532,12 @@ void drain_all_pages(struct zone *zone)
> >
> > #ifdef CONFIG_HIBERNATION
> >
> > +/* Touch watchdog for every WD_INTERVAL_PAGE pages. */
> > +#define WD_INTERVAL_PAGE (100*1024)
> > +
> > void mark_free_pages(struct zone *zone)
> > {
> > - unsigned long pfn, max_zone_pfn;
> > + unsigned long pfn, max_zone_pfn, page_num = 0;
> > unsigned long flags;
> > unsigned int order, t;
> > struct page *page;
> > @@ -2548,6 +2552,9 @@ void mark_free_pages(struct zone *zone)
> > if (pfn_valid(pfn)) {
> > page = pfn_to_page(pfn);
> >
> > + if (!((page_num++) % WD_INTERVAL_PAGE))
> > + touch_nmi_watchdog();
> > +
> > if (page_zone(page) != zone)
> > continue;
> >
> > @@ -2561,8 +2568,11 @@ void mark_free_pages(struct zone *zone)
> > unsigned long i;
> >
> > pfn = page_to_pfn(page);
> > - for (i = 0; i < (1UL << order); i++)
> > + for (i = 0; i < (1UL << order); i++) {
> > + if (!((page_num++) % WD_INTERVAL_PAGE))
> > + touch_nmi_watchdog();
> > swsusp_set_page_free(pfn_to_page(pfn + i));
> > + }
> > }
> > }
> > spin_unlock_irqrestore(&zone->lock, flags);
>
> hm, is it really worth all the WD_INTERVAL_PAGE stuff?
> touch_nmi_watchdog() is pretty efficient and calling it once-per-page
> may not have a measurable effect.
>
We have version 1 of patch to feed the dog once-per-page. And we thought
it might look more elegant if we feed the dog every N pages.
> And if we're really concerned about the performance impact it would be
> better to make WD_INTERVAL_PAGE a power of 2 (128*1024?) to avoid the
> modulus operation.
>
Ok, I'll change the interval to 128*1024 then.
Thanks,
Yu
--
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>
prev parent reply other threads:[~2017-08-22 2:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-21 15:08 [PATCH] PM / Hibernate: Feed the wathdog when creating snapshot Chen Yu
2017-08-21 20:26 ` Andrew Morton
2017-08-22 2:55 ` Chen Yu [this message]
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=20170822025557.GA11870@yu-desktop-1.sh.intel.com \
--to=yu.c.chen@intel.com \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=lenb@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-pm@vger.kernel.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@kernel.org \
--cc=rjw@rjwysocki.net \
--cc=vbabka@suse.cz \
/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).