From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756675Ab3BETXR (ORCPT ); Tue, 5 Feb 2013 14:23:17 -0500 Received: from mail-da0-f46.google.com ([209.85.210.46]:37936 "EHLO mail-da0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754880Ab3BETXL (ORCPT ); Tue, 5 Feb 2013 14:23:11 -0500 Date: Tue, 5 Feb 2013 11:25:20 -0800 From: Greg Kroah-Hartman To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Seth Jennings , Nitin Gupta , Dan Magenheimer , Konrad Rzeszutek Wilk Subject: Re: [PATCH] zsmalloc: Add Kconfig for enabling PTE method Message-ID: <20130205192520.GA8441@kroah.com> References: <1359937421-19921-1-git-send-email-minchan@kernel.org> <20130204185146.GA31284@kroah.com> <20130205000854.GC2610@blaptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130205000854.GC2610@blaptop> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 05, 2013 at 09:08:54AM +0900, Minchan Kim wrote: > Hi Greg, > > On Mon, Feb 04, 2013 at 10:51:46AM -0800, Greg Kroah-Hartman wrote: > > On Mon, Feb 04, 2013 at 09:23:41AM +0900, Minchan Kim wrote: > > > Zsmalloc has two methods 1) copy-based and 2) pte based to access > > > allocations that span two pages. > > > You can see history why we supported two approach from [1]. > > > > > > But it was bad choice that adding hard coding to select architecture > > > which want to use pte based method. This patch removed it and adds > > > new Kconfig to select the approach. > > > > > > This patch is based on next-20130202. > > > > > > [1] https://lkml.org/lkml/2012/7/11/58 > > > > > > Cc: Andrew Morton > > > Cc: Seth Jennings > > > Cc: Nitin Gupta > > > Cc: Dan Magenheimer > > > Cc: Konrad Rzeszutek Wilk > > > Signed-off-by: Minchan Kim > > > --- > > > drivers/staging/zsmalloc/Kconfig | 12 ++++++++++++ > > > drivers/staging/zsmalloc/zsmalloc-main.c | 11 ----------- > > > 2 files changed, 12 insertions(+), 11 deletions(-) > > > > > > diff --git a/drivers/staging/zsmalloc/Kconfig b/drivers/staging/zsmalloc/Kconfig > > > index 9084565..2359123 100644 > > > --- a/drivers/staging/zsmalloc/Kconfig > > > +++ b/drivers/staging/zsmalloc/Kconfig > > > @@ -8,3 +8,15 @@ config ZSMALLOC > > > non-standard allocator interface where a handle, not a pointer, is > > > returned by an alloc(). This handle must be mapped in order to > > > access the allocated space. > > > + > > > +config ZSMALLOC_PGTABLE_MAPPING > > > + bool "Use page table mapping to access allocations that span two pages" > > > + depends on ZSMALLOC > > > + default n > > > + help > > > + By default, zsmalloc uses a copy-based object mapping method to access > > > + allocations that span two pages. However, if a particular architecture > > > + performs VM mapping faster than copying, then you should select this. > > > + This causes zsmalloc to use page table mapping rather than copying > > > + for object mapping. You can check speed with zsmalloc benchmark[1]. > > > + [1] https://github.com/spartacus06/zsmalloc > > > diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c > > > index 06f73a9..b161ca1 100644 > > > --- a/drivers/staging/zsmalloc/zsmalloc-main.c > > > +++ b/drivers/staging/zsmalloc/zsmalloc-main.c > > > @@ -218,17 +218,6 @@ struct zs_pool { > > > #define CLASS_IDX_MASK ((1 << CLASS_IDX_BITS) - 1) > > > #define FULLNESS_MASK ((1 << FULLNESS_BITS) - 1) > > > > > > -/* > > > - * By default, zsmalloc uses a copy-based object mapping method to access > > > - * allocations that span two pages. However, if a particular architecture > > > - * performs VM mapping faster than copying, then it should be added here > > > - * so that USE_PGTABLE_MAPPING is defined. This causes zsmalloc to use > > > - * page table mapping rather than copying for object mapping. > > > -*/ > > > -#if defined(CONFIG_ARM) > > > -#define USE_PGTABLE_MAPPING > > > -#endif > > > > Did you test this? I don't see the new config value you added actually > > do anything in this code. Also, if I select it incorrectly on ARM, or > > *slaps self* Ok, so I'll drop this patch now. As for what to do instead, I have no idea, sorry, but the others should. thanks, greg k-h