From: Peter Zijlstra <peterz@infradead.org>
To: Bharata B Rao <bharata@amd.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
mgorman@suse.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org,
akpm@linux-foundation.org, luto@kernel.org, tglx@linutronix.de,
yue.li@memverge.com, Ravikumar.Bangoria@amd.com,
ying.huang@intel.com
Subject: Re: [RFC PATCH 0/5] Memory access profiler(IBS) driven NUMA balancing
Date: Wed, 8 Feb 2023 19:03:39 +0100 [thread overview]
Message-ID: <Y+Pj+9bbBbHpf6xM@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20230208073533.715-1-bharata@amd.com>
On Wed, Feb 08, 2023 at 01:05:28PM +0530, Bharata B Rao wrote:
> - Perf uses IBS and we are using the same IBS for access profiling here.
> There needs to be a proper way to make the use mutually exclusive.
No, IFF this lives it needs to use in-kernel perf.
> - Is tying this up with NUMA balancing a reasonable approach or
> should we look at a completely new approach?
Is it giving sufficient win to be worth it, afaict it doesn't come even
close to justifying it.
> - Hardware provided access information could be very useful for driving
> hot page promotion in tiered memory systems. Need to check if this
> requires different tuning/heuristics apart from what NUMA balancing
> already does.
I think Huang Ying looked at that from the Intel POV and I think the
conclusion was that it doesn't really work out. What you need is
frequency information, but the PMU doesn't really give you that. You
need to process a *ton* of PMU data in-kernel.
next prev parent reply other threads:[~2023-02-08 18:04 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-08 7:35 Bharata B Rao
2023-02-08 7:35 ` [RFC PATCH 1/5] x86/ibs: In-kernel IBS driver for page access profiling Bharata B Rao
2023-02-08 7:35 ` [RFC PATCH 2/5] x86/ibs: Drive NUMA balancing via IBS access data Bharata B Rao
2023-02-08 7:35 ` [RFC PATCH 3/5] x86/ibs: Enable per-process IBS from sched switch path Bharata B Rao
2023-02-08 7:35 ` [RFC PATCH 4/5] x86/ibs: Adjust access faults sampling period Bharata B Rao
2023-02-08 7:35 ` [RFC PATCH 5/5] x86/ibs: Delay the collection of HW-provided access info Bharata B Rao
2023-02-08 18:03 ` Peter Zijlstra [this message]
2023-02-08 18:12 ` [RFC PATCH 0/5] Memory access profiler(IBS) driven NUMA balancing Dave Hansen
2023-02-09 6:04 ` Bharata B Rao
2023-02-09 14:28 ` Dave Hansen
2023-02-10 4:28 ` Bharata B Rao
2023-02-10 4:40 ` Dave Hansen
2023-02-10 15:10 ` Bharata B Rao
2023-02-09 5:57 ` Bharata B Rao
2023-02-13 2:56 ` Huang, Ying
2023-02-13 3:23 ` Bharata B Rao
2023-02-13 3:34 ` Huang, Ying
2023-02-13 3:26 ` Huang, Ying
2023-02-13 5:52 ` Bharata B Rao
2023-02-13 6:30 ` Huang, Ying
2023-02-14 4:55 ` Bharata B Rao
2023-02-15 6:07 ` Huang, Ying
2023-02-24 3:28 ` Bharata B Rao
2023-02-16 8:41 ` Bharata B Rao
2023-02-17 6:03 ` Huang, Ying
2023-02-24 3:36 ` Bharata B Rao
2023-02-27 7:54 ` Huang, Ying
2023-03-01 11:21 ` Bharata B Rao
2023-03-02 8:10 ` Huang, Ying
2023-03-03 5:25 ` Bharata B Rao
2023-03-03 5:53 ` Huang, Ying
2023-03-06 15:30 ` Bharata B Rao
2023-03-07 2:33 ` Huang, Ying
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