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Date: Tue, 5 Jun 2012 10:52:06 +0300
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Subject: Re: [PATCH 0/5] Some vmevent fixes...
From: Pekka Enberg <penberg@kernel.org>
To: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>, Minchan Kim <minchan@kernel.org>,
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On Mon, Jun 4, 2012 at 11:05 PM, KOSAKI Motohiro
<kosaki.motohiro@gmail.com> wrote:
>> - On desktops, apps can drop their caches on demand if they want to
>>   and can avoid swap activity?
>
> In this case, fallocate(VOLATILE) is work more better.

For some cases, yes, but probably not for all.

For example, if userspace doesn't know about "about to swap real soon"
condition, it can continue to grow its caches making
fallocate(VOLATILE) pretty much useless.