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Date:   Thu, 19 Jan 2023 15:54:56 +0530
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Subject: Re: [RFC PATCH V1 1/1] sched/numa: Enhance vma scanning logic
Content-Language: en-US
To:     Mike Rapoport <rppt@kernel.org>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Valentin Schneider <vschneid@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Liam R . Howlett" <Liam.Howlett@oracle.com>,
        Peter Xu <peterx@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        xu xin <cgel.zte@gmail.com>, Yu Zhao <yuzhao@google.com>,
        Colin Cross <ccross@google.com>, Arnd Bergmann <arnd@arndb.de>,
        Hugh Dickins <hughd@google.com>,
        Bharata B Rao <bharata@amd.com>,
        Disha Talreja <dishaa.talreja@amd.com>
References: <cover.1673610485.git.raghavendra.kt@amd.com>
 <67bf778d592c39d02444825c416c2ed11d2ef4b2.1673610485.git.raghavendra.kt@amd.com>
 <Y8kP2KbJqWDIgGRZ@kernel.org>
From:   Raghavendra K T <raghavendra.kt@amd.com>
In-Reply-To: <Y8kP2KbJqWDIgGRZ@kernel.org>
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On 1/19/2023 3:09 PM, Mike Rapoport wrote:
> Hi,
> 
> On Mon, Jan 16, 2023 at 07:05:34AM +0530, Raghavendra K T wrote:
>>   During the Numa scanning make sure only relevant vmas of the
>> tasks are scanned.
> 
> Please add more detailed description about what are the issues with the
> current scanning this patch aims to solve.

Thank you for the review Mike. Sure will add more detail in the patch
  commit in V2

> 
>> Logic:
>> 1) For the first two time allow unconditional scanning of vmas
>> 2) Store recent 4 unique tasks (last 8bits of PIDs) accessed the vma.
>>    False negetives in case of collison should be fine here.
> 
>           ^ negatives

will take care of this and one below

>> 3) If more than 4 pids exist assume task indeed accessed vma to
>>   to avoid false negetives
>>
>> Co-developed-by: Bharata B Rao <bharata@amd.com>
>> (initial patch to store pid information)
>>
>> Suggested-by: Mel Gorman <mgorman@techsingularity.net>
>> Signed-off-by: Bharata B Rao <bharata@amd.com>
>> Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
>> ---
[...]