linux-kernel - Re: [RFC PATCH] mm: Promote slow memory in advance to improve performance

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Message-ID: <399f9ef5-3a77-902a-7b4c-86020e629944@linux.alibaba.com>
Date:   Tue, 23 Nov 2021 21:20:47 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Yang Shi <shy828301@...il.com>, Mel Gorman <mgorman@...e.de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Huang Ying <ying.huang@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Zi Yan <ziy@...dia.com>, zhongjiang-ali@...ux.alibaba.com,
        Xunlei Pang <xlpang@...ux.alibaba.com>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] mm: Promote slow memory in advance to improve
 performance



On 2021/11/23 3:34, Yang Shi wrote:
> On Mon, Nov 22, 2021 at 2:22 AM Baolin Wang
> <baolin.wang@...ux.alibaba.com> wrote:
>>
>> Some workloads access a set of data entities will follow the data locality,
>> also known as locality of reference, which means the probability of accessing
>> some data soon after some nearby data has been accessed.
>>
>> On some systems with different memory types, which will rely on the numa
>> balancing to promote slow hot memory to fast memory to improve performance.
>> So we can promote several sequential pages on slow memory at one time
>> according to the data locality for some workloads to improve the performance.
> 
> Fault around for NUMA fault definitely could reduce the overhead for
> NUMA balancing by having fewer faults. I think this could be extended
> to regular NUMA balancing too. But I'm not sure whether false
> positives are worth concerning or not.

OK. Like Huang Ying said, maybe we can add some algorithm to adjust the 
window of proactive numa faults dynamically. Thanks for your input.

> 
> I recall Mel proposed fault around too (not in patch, but shared some
> ideas). Added Mel in this thread.