From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f200.google.com (mail-yw0-f200.google.com [209.85.161.200]) by kanga.kvack.org (Postfix) with ESMTP id 8A4A06810D7 for ; Fri, 25 Aug 2017 20:23:00 -0400 (EDT) Received: by mail-yw0-f200.google.com with SMTP id s187so4556498ywf.1 for ; Fri, 25 Aug 2017 17:23:00 -0700 (PDT) Received: from mail-yw0-x22e.google.com (mail-yw0-x22e.google.com. [2607:f8b0:4002:c05::22e]) by mx.google.com with ESMTPS id d61si1934617ybi.804.2017.08.25.17.22.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Aug 2017 17:22:59 -0700 (PDT) Received: by mail-yw0-x22e.google.com with SMTP id h127so6847446ywf.3 for ; Fri, 25 Aug 2017 17:22:59 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170825144957.5d99dad605fed1dc2550d25c@linux-foundation.org> References: <20170818011023.181465-1-shakeelb@google.com> <20170825144957.5d99dad605fed1dc2550d25c@linux-foundation.org> From: Shakeel Butt Date: Fri, 25 Aug 2017 17:22:58 -0700 Message-ID: Subject: Re: [RFC PATCH] mm: fadvise: avoid fadvise for fs without backing device Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Mel Gorman , Johannes Weiner , Hillf Danton , Vlastimil Babka , Hugh Dickins , Greg Thelen , Linux MM , LKML On Fri, Aug 25, 2017 at 2:49 PM, Andrew Morton wrote: > On Thu, 17 Aug 2017 18:20:17 -0700 Shakeel Butt wrote: > >> +linux-mm, linux-kernel >> >> On Thu, Aug 17, 2017 at 6:10 PM, Shakeel Butt 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". > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org