From: Andrew Morton <akpm@linux-foundation.org>
To: Shakeel Butt <shakeelb@google.com>
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 14:49:57 -0700 [thread overview]
Message-ID: <20170825144957.5d99dad605fed1dc2550d25c@linux-foundation.org> (raw)
In-Reply-To: <CALvZod444NZaw9wcdSMs5Y60a0cV4j9SEt-TLBJT34OJ_yg3CQ@mail.gmail.com>
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"?
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next prev parent reply other threads:[~2017-08-25 21:50 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 [this message]
2017-08-26 0:22 ` Shakeel Butt
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