From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com (mail-pa0-f47.google.com [209.85.220.47]) by kanga.kvack.org (Postfix) with ESMTP id 8049C6B0031 for ; Tue, 8 Jul 2014 00:45:18 -0400 (EDT) Received: by mail-pa0-f47.google.com with SMTP id kq14so6643627pab.34 for ; Mon, 07 Jul 2014 21:45:18 -0700 (PDT) Received: from lgeamrelo02.lge.com (lgeamrelo02.lge.com. [156.147.1.126]) by mx.google.com with ESMTP id bp9si5602180pdb.91.2014.07.07.21.45.15 for ; Mon, 07 Jul 2014 21:45:17 -0700 (PDT) Date: Tue, 8 Jul 2014 13:45:18 +0900 From: Minchan Kim Subject: Re: [PATCH v10 1/7] mm: support madvise(MADV_FREE) Message-ID: <20140708044518.GA9824@bbox> References: <1404694438-10272-1-git-send-email-minchan@kernel.org> <1404694438-10272-2-git-send-email-minchan@kernel.org> <53BB6B64.1080807@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <53BB6B64.1080807@cn.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: Zhang Yanfei Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael Kerrisk , Linux API , Hugh Dickins , Johannes Weiner , Rik van Riel , KOSAKI Motohiro , Mel Gorman , Jason Evans , "Kirill A. Shutemov" Hello Zhang, On Tue, Jul 08, 2014 at 11:54:12AM +0800, Zhang Yanfei wrote: > Hi Minchan, > > On 07/07/2014 08:53 AM, Minchan Kim wrote: > > Linux doesn't have an ability to free pages lazy while other OS > > already have been supported that named by madvise(MADV_FREE). > > > > The gain is clear that kernel can discard freed pages rather than > > swapping out or OOM if memory pressure happens. > > > > Without memory pressure, freed pages would be reused by userspace > > without another additional overhead(ex, page fault + allocation > > + zeroing). > > > > How to work is following as. > > > > When madvise syscall is called, VM clears dirty bit of ptes of > > the range. > > This should be updated because the implementation has been changed. > It also remove the page from the swapcache if it is. You're right in current implementation but it's rather one of implementation technique(ie, it could be changed later) but still main main logic from MADV_FREE is tightly coupled with pte dirty bit so I don't feel I added it in description but it would be better to add it as comment. Thanks for the review! > > Thank you for your effort! > > -- > Thanks. > Zhang Yanfei > > -- > 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 -- Kind regards, Minchan Kim -- 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