From: Peter Zijlstra <peterz@infradead.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>, Rik van Riel <riel@redhat.com>,
Mel Gorman <mgorman@suse.de>, Ingo Molnar <mingo@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Fengguang Wu <fengguang.wu@intel.com>
Subject: Re: [RFC 10/10] autonuma, memory tiering: Adjust hot threshold automatically
Date: Mon, 4 Nov 2019 09:49:24 +0100 [thread overview]
Message-ID: <20191104084924.GB4131@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <877e4gcgsg.fsf@yhuang-dev.intel.com>
On Mon, Nov 04, 2019 at 02:11:11PM +0800, Huang, Ying wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
>
> > On Fri, Nov 01, 2019 at 03:57:27PM +0800, Huang, Ying wrote:
> >
> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >> index 0a83e9cf6685..22bdbb7afac2 100644
> >> --- a/kernel/sched/fair.c
> >> +++ b/kernel/sched/fair.c
> >> @@ -1486,6 +1486,41 @@ static bool numa_migration_check_rate_limit(struct pglist_data *pgdat,
> >> return true;
> >> }
> >>
> >> +#define NUMA_MIGRATION_ADJUST_STEPS 16
> >> +
> >> +static void numa_migration_adjust_threshold(struct pglist_data *pgdat,
> >> + unsigned long rate_limit,
> >> + unsigned long ref_threshold)
> >> +{
> >> + unsigned long now = jiffies, last_threshold_jiffies;
> >> + unsigned long unit_threshold, threshold;
> >> + unsigned long try_migrate, ref_try_migrate, mdiff;
> >> +
> >> + last_threshold_jiffies = pgdat->autonuma_threshold_jiffies;
> >> + if (now > last_threshold_jiffies +
> >> + msecs_to_jiffies(sysctl_numa_balancing_scan_period_max) &&
> >> + cmpxchg(&pgdat->autonuma_threshold_jiffies,
> >> + last_threshold_jiffies, now) == last_threshold_jiffies) {
> >
> > That is seriously unreadable gunk.
>
> The basic idea here is to adjust hot threshold every
Oh, I figured out what it does, but it's just really hard to read
because of those silly variable names.
This was just a first quick read through of the patches, and stuff like
this annoys me no end. I did start a rewrite with more sensible variable
names, but figured this might not be time for that.
I still need to think and review the whole concept in more detail, now
that I've read the patches. But I need to chase regressions first :/
FWIW, can you post a SLIT / NUMA distance table for such a system?
next prev parent reply other threads:[~2019-11-04 8:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-01 7:57 [RFC 00/10] autonuma: Optimize memory placement in memory tiering system Huang, Ying
2019-11-01 7:57 ` [RFC 01/10] autonuma: Fix watermark checking in migrate_balanced_pgdat() Huang, Ying
2019-11-01 11:11 ` Mel Gorman
2019-11-01 7:57 ` [RFC 02/10] autonuma: Reduce cache footprint when scanning page tables Huang, Ying
2019-11-01 11:13 ` Mel Gorman
2019-11-01 7:57 ` [RFC 03/10] autonuma: Add NUMA_BALANCING_MEMORY_TIERING mode Huang, Ying
2019-11-01 7:57 ` [RFC 04/10] autonuma, memory tiering: Rate limit NUMA migration throughput Huang, Ying
2019-11-01 7:57 ` [RFC 05/10] autonuma, memory tiering: Use kswapd to demote cold pages to PMEM Huang, Ying
2019-11-01 7:57 ` [RFC 06/10] autonuma, memory tiering: Skip to scan fastest memory Huang, Ying
2019-11-01 7:57 ` [RFC 07/10] autonuma, memory tiering: Only promote page if accessed twice Huang, Ying
2019-11-01 7:57 ` [RFC 08/10] autonuma, memory tiering: Select hotter pages to promote to fast memory node Huang, Ying
2019-11-01 9:24 ` Peter Zijlstra
2019-11-04 2:41 ` Huang, Ying
2019-11-04 8:44 ` Peter Zijlstra
2019-11-04 10:13 ` Huang, Ying
2019-11-01 7:57 ` [RFC 09/10] autonuma, memory tiering: Double hot threshold for write hint page fault Huang, Ying
2019-11-01 7:57 ` [RFC 10/10] autonuma, memory tiering: Adjust hot threshold automatically Huang, Ying
2019-11-01 9:31 ` Peter Zijlstra
2019-11-04 6:11 ` Huang, Ying
2019-11-04 8:49 ` Peter Zijlstra [this message]
2019-11-04 10:12 ` Huang, Ying
2019-11-21 8:38 ` Huang, Ying
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=20191104084924.GB4131@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=fengguang.wu@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=mhocko@suse.com \
--cc=mingo@kernel.org \
--cc=riel@redhat.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