linux-kernel - Re: [PATCH v2 3/3] mm/mempolicy: introduce MPOL_WEIGHTED

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Date: Tue, 23 Jan 2024 00:16:12 -0500
From: Gregory Price <gregory.price@...verge.com>
To: "Huang, Ying" <ying.huang@...el.com>
Cc: Gregory Price <gourry.memverge@...il.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
	corbet@....net, akpm@...ux-foundation.org, honggyu.kim@...com,
	rakie.kim@...com, hyeongtak.ji@...com, mhocko@...nel.org,
	vtavarespetr@...ron.com, jgroves@...ron.com,
	ravis.opensrc@...ron.com, sthanneeru@...ron.com,
	emirakhur@...ron.com, Hasan.Maruf@....com, seungjun.ha@...sung.com,
	hannes@...xchg.org, dan.j.williams@...el.com,
	Srinivasulu Thanneeru <sthanneeru.opensrc@...ron.com>
Subject: Re: [PATCH v2 3/3] mm/mempolicy: introduce MPOL_WEIGHTED_INTERLEAVE
 for weighted interleaving

On Mon, Jan 22, 2024 at 11:54:34PM -0500, Gregory Price wrote:
> > 
> > Can the above code be simplified as something like below?
> > 
> >         resume_node = prev_node;
---         resume_weight = 0;
+++         resume_weight = weights[node];
> >         for (...) {
> >                 ...
> >         }
> > 
> 
> I'll take another look at it, but this logic is annoying because of the
> corner case:  me->il_prev can be NUMA_NO_NODE or an actual numa node.
> 

After a quick look, as long as no one objects to (me->il_prev) remaining
NUMA_NO_NODE while having a weight assigned to pol->wil.cur_weight, then
this looks like it can be simplified as above.

I don't think it's harmful, but i'll have to take a quick look at what
happens on rebind to make sure we don't have a stale weight.

~Gregory