From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26E34C433E0 for ; Wed, 3 Feb 2021 19:42:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC6A964F5F for ; Wed, 3 Feb 2021 19:42:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230218AbhBCTmi (ORCPT ); Wed, 3 Feb 2021 14:42:38 -0500 Received: from mga18.intel.com ([134.134.136.126]:31775 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbhBCTmc (ORCPT ); Wed, 3 Feb 2021 14:42:32 -0500 IronPort-SDR: MF7m5DVHJ9MqvZJjqp1rOvQ1Y9goDrDYOivSPOWi/UOmQv+uAa0cvb3+jdf+XRJ2dHwsvCiaSi jjxJREMdDDxQ== X-IronPort-AV: E=McAfee;i="6000,8403,9884"; a="168786540" X-IronPort-AV: E=Sophos;i="5.79,399,1602572400"; d="scan'208";a="168786540" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Feb 2021 11:42:12 -0800 IronPort-SDR: 5PXk2IM/lL7HaK0MhY3Qyh8dIXUEIa71n2wUZ67klgH2pq/sIM5IXz8kGgGiG5t6xtWepomcl/ GbHMGxsFrRYg== X-IronPort-AV: E=Sophos;i="5.79,399,1602572400"; d="scan'208";a="576012095" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Feb 2021 11:42:12 -0800 Date: Wed, 3 Feb 2021 11:42:11 -0800 From: Ira Weiny To: Prathu Baronia Cc: linux-kernel@vger.kernel.org, chintan.pandya@oneplus.com, Prathu Baronia , Andrew Morton , Thomas Gleixner , "Peter Zijlstra (Intel)" , Randy Dunlap , "Matthew Wilcox (Oracle)" Subject: Re: [PATCH v2 1/1] mm: Optimizing hugepage zeroing in arm64 Message-ID: <20210203194211.GE3200985@iweiny-DESK2.sc.intel.com> References: <20210202074225.7244-1-prathu.baronia@oneplus.com> <20210202074225.7244-2-prathu.baronia@oneplus.com> <20210202200354.GB3200985@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.11.1 (2018-12-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 03, 2021 at 04:08:08PM +0530, Prathu Baronia wrote: > Hey Ira, > I looked at your below-mentioned patch and I agree that the > above-mentioned functions also need modification similar to > clear_user_highpage(). > Would it be okay with you if I send your patch again with a modified > commit message by adding my data and maintaining your authorship? > [1]https://lore.kernel.org/lkml/20201210171834.2472353-2-ira.weiny@intel.com/ Sure. I have not changed the patch at all from that version. Andrew, will this be going through your tree? If not who? If you take the above patch I can drop it from the series I'm about to submit to convert btrfs kmaps. Ira > Regards, > Prathu Baronia > > On Wed, Feb 3, 2021 at 1:33 AM Ira Weiny <[2]ira.weiny@intel.com> wrote: > > On Tue, Feb 02, 2021 at 01:12:24PM +0530, Prathu Baronia wrote: > > In !HIGHMEM cases, specially in 64-bit architectures, we don't need > temp > > mapping of pages. Hence, k(map|unmap)_atomic() acts as nothing more > than > > multiple barrier() calls, for example for a 2MB hugepage in > > clear_huge_page() these are called 512 times i.e. to map and unmap > each > > subpage that means in total 2048 barrier calls. This called for > > optimization. Simply getting VADDR from page in the form of > kmap_local_* > > APIs does the job for us.  We profiled clear_huge_page() using ftrace > > and observed an improvement of 62%. > > Nice! > > > > > Setup:- > > Below data has been collected on Qualcomm's SM7250 SoC THP enabled > > (kernel > > v4.19.113) with only CPU-0(Cortex-A55) and CPU-7(Cortex-A76) switched > on > > and set to max frequency, also DDR set to perf governor. > > > > FTRACE Data:- > > > > Base data:- > > Number of iterations: 48 > > Mean of allocation time: 349.5 us > > std deviation: 74.5 us > > > > v1 data:- > > Number of iterations: 48 > > Mean of allocation time: 131 us > > std deviation: 32.7 us > > > > The following simple userspace experiment to allocate > > 100MB(BUF_SZ) of pages and writing to it gave us a good insight, > > we observed an improvement of 42% in allocation and writing timings. > > ------------------------------------------------------------- > > Test code snippet > > ------------------------------------------------------------- > >       clock_start(); > >       buf = malloc(BUF_SZ); /* Allocate 100 MB of memory */ > > > >         for(i=0; i < BUF_SZ_PAGES; i++) > >         { > >                 *((int *)(buf + (i*PAGE_SIZE))) = 1; > >         } > >       clock_end(); > > ------------------------------------------------------------- > > > > Malloc test timings for 100MB anon allocation:- > > > > Base data:- > > Number of iterations: 100 > > Mean of allocation time: 31831 us > > std deviation: 4286 us > > > > v1 data:- > > Number of iterations: 100 > > Mean of allocation time: 18193 us > > std deviation: 4915 us > > > > Reported-by: Chintan Pandya <[3]chintan.pandya@oneplus.com> > > Signed-off-by: Prathu Baronia <[4]prathu.baronia@oneplus.com> > > Reviewed-by: Ira Weiny <[5]ira.weiny@intel.com> > > FWIW, I have the same change in a patch in my kmap() changes branch.  > However, > my patch also changes clear_highpage(), zero_user_segments(), > copy_user_highpage(), and copy_highpage(). > > Would changing those help you as well? > > Ira > > > --- > >  include/linux/highmem.h | 4 ++-- > >  1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > > index d2c70d3772a3..444df139b489 100644 > > --- a/include/linux/highmem.h > > +++ b/include/linux/highmem.h > > @@ -146,9 +146,9 @@ static inline void > invalidate_kernel_vmap_range(void *vaddr, int size) > >  #ifndef clear_user_highpage > >  static inline void clear_user_highpage(struct page *page, unsigned > long vaddr) > >  { > > -     void *addr = kmap_atomic(page); > > +     void *addr = kmap_local_page(page); > >       clear_user_page(addr, vaddr, page); > > -     kunmap_atomic(addr); > > +     kunmap_local(addr); > >  } > >  #endif > >  > > -- > > 2.17.1 > > > > References > > Visible links > 1. https://lore.kernel.org/lkml/20201210171834.2472353-2-ira.weiny@intel.com/ > 2. mailto:ira.weiny@intel.com > 3. mailto:chintan.pandya@oneplus.com > 4. mailto:prathu.baronia@oneplus.com > 5. mailto:ira.weiny@intel.com