From: Shakeel Butt <shakeelb@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Hillf Danton <hillf.zj@alibaba-inc.com>,
Vlastimil Babka <vbabka@suse.cz>, Hugh Dickins <hughd@google.com>,
Greg Thelen <gthelen@google.com>, Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device
Date: Fri, 25 Aug 2017 17:22:58 -0700 [thread overview]
Message-ID: <CALvZod5nvGtHAduA89Ak5gOofJVMA7bhmXjRrjseTptoqz+cmA@mail.gmail.com> (raw)
In-Reply-To: <20170825144957.5d99dad605fed1dc2550d25c@linux-foundation.org>
On Fri, Aug 25, 2017 at 2:49 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Thu, 17 Aug 2017 18:20:17 -0700 Shakeel Butt <shakeelb@google.com> wrote:
>
>> +linux-mm, linux-kernel
>>
>> On Thu, Aug 17, 2017 at 6:10 PM, Shakeel Butt <shakeelb@google.com> wrote:
>> > The fadvise() manpage is silent on fadvise()'s effect on
>> > memory-based filesystems (shmem, hugetlbfs & ramfs) and pseudo
>> > file systems (procfs, sysfs, kernfs). The current implementaion
>> > of fadvise is mostly a noop for such filesystems except for
>> > FADV_DONTNEED which will trigger expensive remote LRU cache
>> > draining. This patch makes the noop of fadvise() on such file
>> > systems very explicit.
>> >
>> > However this change has two side effects for ramfs and one for
>> > tmpfs. First fadvise(FADV_DONTNEED) can remove the unmapped clean
>> > zero'ed pages of ramfs (allocated through read, readahead & read
>> > fault) and tmpfs (allocated through read fault). Also
>> > fadvise(FADV_WILLNEED) on create such clean zero'ed pages for
>> > ramfs.
>
> That sentence makes no sense. I assume "fadvise(FADV_WILLNEED) will
> create"?
>
Sorry about that, it should be "fadvise(FADV_WILLNEED) can create".
>
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prev parent reply other threads:[~2017-08-26 0:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170818011023.181465-1-shakeelb@google.com>
2017-08-18 1:20 ` [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device Shakeel Butt
2017-08-18 21:34 ` Andrew Morton
2017-08-18 23:17 ` Shakeel Butt
2017-08-23 0:25 ` Shakeel Butt
2017-08-25 21:49 ` Andrew Morton
2017-08-26 0:22 ` Shakeel Butt [this message]
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