linux-kernel - Re: [PATCH v5 0/4] mm/page_reporting: Make page reporting work on arm64 with 64KB page size

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Message-ID: <cfe870da-89a4-cac7-814b-0c3a540d25c0@redhat.com>
Date:   Mon, 28 Jun 2021 19:45:30 +1000
From:   Gavin Shan <gshan@...hat.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        David Hildenbrand <david@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, shan.gavin@...il.com
Subject: Re: [PATCH v5 0/4] mm/page_reporting: Make page reporting work on
 arm64 with 64KB page size

On 6/26/21 12:18 AM, Alexander Duyck wrote:
> On Thu, Jun 24, 2021 at 7:20 PM Gavin Shan <gshan@...hat.com> wrote:
>>
>> The page reporting threshold is currently equal to @pageblock_order, which
>> is 13 and 512MB on arm64 with 64KB base page size selected. The page
>> reporting won't be triggered if the freeing page can't come up with a free
>> area like that huge. The condition is hard to be met, especially when the
>> system memory becomes fragmented.
>>
>> This series intends to solve the issue by having page reporting threshold
>> as 5 (2MB) on arm64 with 64KB base page size. The patches are organized as:
>>
>>     PATCH[1/4] Fix some coding style in __page_reporting_request().
>>     PATCH[2/4] Represents page reporting order with variable so that it can
>>                be exported as module parameter.
>>     PATCH[3/4] Allows the device driver (e.g. virtio_balloon) to specify
>>                the page reporting order when the device info is registered.
>>     PATCH[4/4] Specifies the page reporting order to 5, corresponding to
>>                2MB in size on ARM64 when 64KB base page size is used.
>>
>> Changelog
>> =========
>> v5:
>>     * Restore @page_reporting_order to @pageblock_order when
>>       device is registered in PATCH[2/4] to keep "git bisect"
>>       friendly at least.                                           (Alex)
> 
> These latest changes address the concerns I had.
> 

Thanks again for your review, Alex. However, v4 was merged and it's fine
since v5 only resolves 'git-bisect' friendly issue on PATCH[v4 2/4].

Thanks,
Gavin