linux-kernel - Re: [PATCH v3 1/7] mm: demotion: Fix demotion targets sharing among sources

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Message-ID: <9581e4acc5392fd3f173189f7bd3ed11c372883e.camel@intel.com>
Date:   Tue, 26 Apr 2022 15:26:56 +0800
From:   "ying.huang@...el.com" <ying.huang@...el.com>
To:     Jagdish Gediya <jvgediya@...ux.ibm.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, baolin.wang@...ux.alibaba.com,
        dave.hansen@...ux.intel.com, aneesh.kumar@...ux.ibm.com,
        shy828301@...il.com, weixugc@...gle.com, gthelen@...gle.com,
        dan.j.williams@...el.com
Subject: Re: [PATCH v3 1/7] mm: demotion: Fix demotion targets sharing among
 sources

On Mon, 2022-04-25 at 15:02 +0530, Jagdish Gediya wrote:
> On Sun, Apr 24, 2022 at 11:25:50AM +0800, ying.huang@...el.com wrote:
> > > Subject: [PATCH v3 1/7] mm: demotion: Fix demotion targets sharing among sources
> > 
> > IMHO, this patch doesn't fix some bugs in the original code.  Instead,
> > it just enhances the original code.  For example, the subject could be,
> 
> I think it is fixing a bug, there is a comment in the code which
> mentions that 'used_targets will become unavailable in future passes.
> This limits some opportunities for multiple source nodes to share a
> destination'. As per this comment, it was intended to share a node as
> demotion targets with some limits but the code limits not some but all
> such opportunities as no common node can be demotion targets for
> multiple source node as per current code.

IMHO, the original code is just to keep as simple as possible to address
the issue for the real machines at that time.  That provides a base line
for future improvement like you have done.  If the original code
wouldn't work well for the target machines, then we fixed a bug.  But if
that doen't work well for some new kind of machines, then we need to
improve the code, add more feature, not to fix a bug.

Best Regards,
Huang, Ying

> >   mm: demotion: support to share demotion targets among sources
> > 
> > Best Regards,
> > Huang, Ying
> > 
> > [snip]
> > 
> > 
> >