Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
IronPort-SDR: kEggzGRjQUbhQNgPmmQt5XZjqmvhOZQFx2qGTmem87b+uhUWRsd7lY08kKes4pYB2fJ2QwHwLX
 yoqe9nN7w4QQ==
Subject: Re: [PATCH v16.1 0/9] mm / virtio: Provide support for free page
 reporting
To:     Hillf Danton <hdanton@sina.com>
CC:     Alexander Duyck <alexander.duyck@gmail.com>, <kvm@vger.kernel.org>,
        <mst@redhat.com>, <linux-kernel@vger.kernel.org>,
        <linux-mm@kvack.org>, <akpm@linux-foundation.org>,
        <mgorman@techsingularity.net>, Minchan Kim <minchan@kernel.org>,
        <vbabka@suse.cz>
References: <20200122173040.6142.39116.stgit@localhost.localdomain>
 <20200124132352.12824-1-hdanton@sina.com>
From:   Alexander Graf <graf@amazon.com>
Message-ID: <286cae85-5dc0-50a7-4fb1-96e75cef408d@amazon.com>
Date:   Fri, 24 Jan 2020 17:40:51 +0100
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0)
 Gecko/20100101 Thunderbird/68.4.1
MIME-Version: 1.0
In-Reply-To: <20200124132352.12824-1-hdanton@sina.com>
Content-Language: en-US
Content-Type: text/plain; charset="windows-1252"; format="flowed"
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 24.01.20 14:23, Hillf Danton wrote:
> =

> On Thu, 23 Jan 2020 11:20:07 +0100 Alexander Graf wrote:
>>
>> The big problem I see is that what I really want from a user's point of
>> view is a tuneable that says "Automatically free clean page cache pages
>> that were not accessed in the last X minutes".
> =

> A diff is made on top of 1a4e58cce84e ("mm: introduce MADV_PAGEOUT") with=
out
> test in any form, assuming it goes in line with the tunable above but wit=
hout
> "X minutes" taken into account.
> =

> [BTW, please take a look at
> Content-Type: text/plain; charset=3D"utf-8"; format=3D"flowed"
> Content-Transfer-Encoding: base64
Thanks, looks like Exchange doesn't pass 8bit data on, I've changed the =

default to ascii now, please just notify me in private if you see it =

broken again.

> =

> and ensure pure text message.]
> =

> =

> --- a/include/uapi/asm-generic/mman-common.h
> +++ b/include/uapi/asm-generic/mman-common.h
> @@ -69,6 +69,7 @@
>   =

>   #define MADV_COLD	20		/* deactivate these pages */
>   #define MADV_PAGEOUT	21		/* reclaim these pages */
> +#define MADV_CCPC	22		/* reclaim cold & clean page cache pages */

This patch adds a new madvise flag. I have a hard time seeing how that =

would help with the "full system expiry" of pages?

The basic point that I tried to make above was that I would ideally like =

to have a coldness cutoff date at which you can be pretty confident that =

page cache data is no longer needed.

To work properly, this needs to be transparent to any normal process on =

the system :).


Alex


Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879