From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 268EE6B0038 for ; Mon, 25 Sep 2017 02:30:31 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id r83so11941058pfj.5 for ; Sun, 24 Sep 2017 23:30:31 -0700 (PDT) Received: from lgeamrelo11.lge.com (LGEAMRELO11.lge.com. [156.147.23.51]) by mx.google.com with ESMTP id 186si3107494pfa.91.2017.09.24.23.30.29 for ; Sun, 24 Sep 2017 23:30:30 -0700 (PDT) Date: Mon, 25 Sep 2017 15:30:28 +0900 From: Minchan Kim Subject: Re: [PATCH] mm, swap: Make VMA based swap readahead configurable Message-ID: <20170925063028.GA27727@bbox> References: <20170921013310.31348-1-ying.huang@intel.com> <20170925054133.GB27410@bbox> <87bmlze319.fsf@yhuang-dev.intel.com> <20170925061734.GA27678@bbox> <87377be1n5.fsf@yhuang-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87377be1n5.fsf@yhuang-dev.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Huang, Ying" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Rik van Riel , Shaohua Li , Hugh Dickins , Fengguang Wu , Tim Chen , Dave Hansen On Mon, Sep 25, 2017 at 02:24:46PM +0800, Huang, Ying wrote: > Minchan Kim writes: > > > On Mon, Sep 25, 2017 at 01:54:42PM +0800, Huang, Ying wrote: > >> Hi, Minchan, > >> > >> Minchan Kim writes: > >> > >> > Hi Huang, > >> > > >> > On Thu, Sep 21, 2017 at 09:33:10AM +0800, Huang, Ying wrote: > >> >> From: Huang Ying > >> > >> [snip] > >> > >> >> diff --git a/mm/Kconfig b/mm/Kconfig > >> >> index 9c4bdddd80c2..e62c8e2e34ef 100644 > >> >> --- a/mm/Kconfig > >> >> +++ b/mm/Kconfig > >> >> @@ -434,6 +434,26 @@ config THP_SWAP > >> >> > >> >> For selection by architectures with reasonable THP sizes. > >> >> > >> >> +config VMA_SWAP_READAHEAD > >> >> + bool "VMA based swap readahead" > >> >> + depends on SWAP > >> >> + default y > >> >> + help > >> >> + VMA based swap readahead detects page accessing pattern in a > >> >> + VMA and adjust the swap readahead window for pages in the > >> >> + VMA accordingly. It works better for more complex workload > >> >> + compared with the original physical swap readahead. > >> >> + > >> >> + It can be controlled via the following sysfs interface, > >> >> + > >> >> + /sys/kernel/mm/swap/vma_ra_enabled > >> >> + /sys/kernel/mm/swap/vma_ra_max_order > >> > > >> > It might be better to discuss in other thread but if you mention new > >> > interface here again, I will discuss it here. > >> > > >> > We are creating new ABI in here so I want to ask question in here. > >> > > >> > Did you consier to use /sys/block/xxx/queue/read_ahead_kb for the > >> > swap readahead knob? Reusing such common/consistent knob would be better > >> > than adding new separate konb. > >> > >> The problem is that the configuration of VMA based swap readahead is > >> global instead of block device specific. And because it works in > >> virtual way, that is, the swap blocks on the different block devices may > >> be readahead together. It's a little hard to use the block device > >> specific configuration. > > > > Fair enough. page-cluster from the beginning should have been like that > > instead of vma_ra_max_order. > > > > One more questions: Do we need separate vma_ra_enable? > > > > Can't we disable it via echo 0 > /sys/kernel/mm/swap/vma_ra_max_order > > like page-cluster? > > The difference is, > > vma_ra_eanble: 0 > => use original physical swap readahead > > vma_ra_enable: 1 && vma_ra_max_order: 0 > => use VMA based swap readahead and disable the readahead. I understand now. Thanks! -- 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