linux-kernel - Re: [PATCH RESEND] autonuma: Fix scan period updating

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Message-Id: <20190726092021.GA5273@linux.vnet.ibm.com>
Date:   Fri, 26 Jul 2019 14:50:21 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     "Huang, Ying" <ying.huang@...el.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Rik van Riel <riel@...hat.com>,
        Mel Gorman <mgorman@...e.de>, jhladky@...hat.com,
        lvenanci@...hat.com, Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH RESEND] autonuma: Fix scan period updating

* Huang, Ying <ying.huang@...el.com> [2019-07-26 15:45:39]:

> Hi, Srikar,
> 
> >
> > More Remote + Private page Accesses:
> > Most likely the Private accesses are going to be local accesses.
> >
> > In the unlikely event of the private accesses not being local, we should
> > scan faster so that the memory and task consolidates.
> >
> > More Remote + Shared page Accesses: This means the workload has not
> > consolidated and needs to scan faster. So we need to scan faster.
> 
> This sounds reasonable.  But
> 
> lr_ratio < NUMA_PERIOD_THRESHOLD
> 
> doesn't indicate More Remote.  If Local = Remote, it is also true.  If

less lr_ratio means more remote.

> there are also more Shared, we should slow down the scanning.  So, the

Why should we slowing down if there are more remote shared accesses?

> logic could be
> 
> if (lr_ratio >= NUMA_PERIOD_THRESHOLD)
>     slow down scanning
> else if (sp_ratio >= NUMA_PERIOD_THRESHOLD) {
>     if (NUMA_PERIOD_SLOTS - lr_ratio >= NUMA_PERIOD_THRESHOLD)
>         speed up scanning
>     else
>         slow down scanning
> } else
>    speed up scanning
> 
> This follows your idea better?
> 
> Best Regards,
> Huang, Ying

-- 
Thanks and Regards
Srikar Dronamraju