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From: Andrew Morton <akpm@linux-foundation.org>
To: Gregory Price <gourry@gourry.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>,
	hyeonggon.yoo@sk.com, ying.huang@linux.alibaba.com,
	honggyu.kim@sk.com, rafael@kernel.org, lenb@kernel.org,
	gregkh@linuxfoundation.org, rakie.kim@sk.com,
	dan.j.williams@intel.com, Jonathan.Cameron@huawei.com,
	dave.jiang@intel.com, horen.chuang@linux.dev, hannes@cmpxchg.org,
	linux-kernel@vger.org, linux-acpi@vger.kernel.org,
	linux-mm@kvack.org, kernel-team@meta.com
Subject: Re: [PATCH v5] mm/mempolicy: Weighted Interleave Auto-tuning
Date: Mon, 10 Feb 2025 16:39:41 -0800	[thread overview]
Message-ID: <20250210163941.15da1e935ed47aacf810fdd0@linux-foundation.org> (raw)
In-Reply-To: <Z6mQUIAOTvHj3wSp@gourry-fedora-PF4VCD3F>

On Mon, 10 Feb 2025 00:36:16 -0500 Gregory Price <gourry@gourry.net> wrote:

> On Fri, Feb 07, 2025 at 06:20:09PM -0800, Andrew Morton wrote:
> > On Fri,  7 Feb 2025 12:13:35 -0800 Joshua Hahn <joshua.hahnjy@gmail.com> wrote:
> > 
> > Leading to... how do we know that this patch makes the kernel better?
> 
> Just focusing on this question:
> 
> The default behavior of weighted interleave without this patch is
> equivalent to normal interleave.  This provides a differentiation
> out-of-the box, and that's just a better experience.
> 
> We may find the default values / calculations need tweaking in the
> future, but this gives us a good starting point.  Anecdotally, I've
> seen an "optimal" distribution of 10:1 based on the numbers run
> sub-optimally compared to 7:1 or 13:1 (but better than default mempol).

How was this optimality measured/observed?

> So there will always be a "try it and see" component to this.
> 
> (Not to mention hardware/firmware lies regularly, and their reported
>  performance numbers rarely if ever match their tested numbers - so
>  *at best* this can be considered a best-effort feature)



  reply	other threads:[~2025-02-11  0:39 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-07 20:13 Joshua Hahn
2025-02-08  2:20 ` Andrew Morton
2025-02-08  5:06   ` Joshua Hahn
2025-02-12  0:17     ` Andrew Morton
2025-02-12 15:26       ` Joshua Hahn
2025-02-10  5:36   ` Gregory Price
2025-02-11  0:39     ` Andrew Morton [this message]
2025-02-11  2:14       ` Gregory Price
2025-02-08  6:51 ` Oscar Salvador
2025-02-12 15:18   ` Joshua Hahn
2025-02-12  2:49 ` Huang, Ying
2025-02-12 17:06   ` Joshua Hahn
2025-02-13  1:32     ` Huang, Ying
2025-02-14 15:45       ` Joshua Hahn
2025-02-16  0:40         ` Huang, Ying

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