From: Mel Gorman <mgorman@techsingularity.net>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/4] sched/numa: Apply imbalance limitations consistently
Date: Wed, 18 May 2022 16:39:47 +0100 [thread overview]
Message-ID: <20220518153947.GS3441@techsingularity.net> (raw)
In-Reply-To: <YoT7xtVc0f3DVCKL@hirez.programming.kicks-ass.net>
On Wed, May 18, 2022 at 03:59:34PM +0200, Peter Zijlstra wrote:
> On Wed, May 18, 2022 at 11:46:52AM +0100, Mel Gorman wrote:
>
> > > (Although I do wonder about that 25% figure in the comment; that doesn't
> > > seem to relate to any actual code anymore)
> > >
> >
> > You're right, by the end of the series it's completely inaccurate and
> > currently it's not accurate if there are multiple LLCs per node. I
> > adjusted the wording to "Allow a NUMA imbalance if busy CPUs is less
> > than the maximum threshold. Above this threshold, individual tasks may
> > be contending for both memory bandwidth and any shared HT resources."
> >
>
> Looks good. Meanwhile I saw a 0-day complaint that this regresses
> something something unixbench by a bit. Do we care enough? I suppose
> this is one of those trade-off patches again, win some, loose some.
I think it's a trade-off. I made a more complete response to the 0-day
people at https://lore.kernel.org/all/20220518152258.GR3441@techsingularity.net/
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2022-05-18 15:40 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-11 14:30 [PATCH 0/4] Mitigate inconsistent NUMA imbalance behaviour Mel Gorman
2022-05-11 14:30 ` [PATCH 1/4] sched/numa: Initialise numa_migrate_retry Mel Gorman
2022-05-11 14:30 ` [PATCH 2/4] sched/numa: Do not swap tasks between nodes when spare capacity is available Mel Gorman
2022-05-11 14:30 ` [PATCH 3/4] sched/numa: Apply imbalance limitations consistently Mel Gorman
2022-05-18 9:24 ` [sched/numa] bb2dee337b: unixbench.score -11.2% regression kernel test robot
2022-05-18 15:22 ` Mel Gorman
2022-05-19 7:54 ` ying.huang
2022-05-20 6:44 ` [LKP] " Ying Huang
2022-05-18 9:31 ` [PATCH 3/4] sched/numa: Apply imbalance limitations consistently Peter Zijlstra
2022-05-18 10:46 ` Mel Gorman
2022-05-18 13:59 ` Peter Zijlstra
2022-05-18 15:39 ` Mel Gorman [this message]
2022-05-11 14:30 ` [PATCH 4/4] sched/numa: Adjust imb_numa_nr to a better approximation of memory channels Mel Gorman
2022-05-18 9:41 ` Peter Zijlstra
2022-05-18 11:15 ` Mel Gorman
2022-05-18 14:05 ` Peter Zijlstra
2022-05-18 17:06 ` Mel Gorman
2022-05-19 9:29 ` Mel Gorman
2022-05-20 4:58 ` [PATCH 0/4] Mitigate inconsistent NUMA imbalance behaviour K Prateek Nayak
2022-05-20 10:18 ` Mel Gorman
2022-05-20 15:17 ` K Prateek Nayak
-- strict thread matches above, loose matches on Subject: below --
2022-05-20 10:35 [PATCH v2 " Mel Gorman
2022-05-20 10:35 ` [PATCH 3/4] sched/numa: Apply imbalance limitations consistently Mel Gorman
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