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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40B8AC6FD19 for ; Thu, 16 Mar 2023 16:36:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231253AbjCPQgz (ORCPT ); Thu, 16 Mar 2023 12:36:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231248AbjCPQgS (ORCPT ); Thu, 16 Mar 2023 12:36:18 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4F0EEE6FC5; Thu, 16 Mar 2023 09:35:28 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DC2BB2F4; Thu, 16 Mar 2023 09:35:14 -0700 (PDT) Received: from [10.1.30.156] (C02CF1NRLVDN.cambridge.arm.com [10.1.30.156]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 717313F885; Thu, 16 Mar 2023 09:34:30 -0700 (PDT) Message-ID: Date: Thu, 16 Mar 2023 16:34:29 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v4 34/36] rmap: add folio_add_file_rmap_range() Content-Language: en-US To: "Yin, Fengwei" , "Matthew Wilcox (Oracle)" , linux-arch@vger.kernel.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230315051444.3229621-1-willy@infradead.org> <20230315051444.3229621-35-willy@infradead.org> <387dc921-de2b-f244-985c-d1e6336d5909@arm.com> <01071d9c-483f-2d95-87a6-e1030acaf8dd@arm.com> <0f581d0d-3139-4007-2161-592a0a545b50@intel.com> From: Ryan Roberts In-Reply-To: <0f581d0d-3139-4007-2161-592a0a545b50@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On 16/03/2023 16:27, Yin, Fengwei wrote: > Hi Matthew, > > On 3/16/2023 12:08 AM, Ryan Roberts wrote: >> On 15/03/2023 13:34, Ryan Roberts wrote: >>> On 15/03/2023 05:14, Matthew Wilcox (Oracle) wrote: >>>> From: Yin Fengwei >>>> >>>> folio_add_file_rmap_range() allows to add pte mapping to a specific >>>> range of file folio. Comparing to page_add_file_rmap(), it batched >>>> updates __lruvec_stat for large folio. >>>> >>>> Signed-off-by: Yin Fengwei >>>> Signed-off-by: Matthew Wilcox (Oracle) >>>> --- >>>> include/linux/rmap.h | 2 ++ >>>> mm/rmap.c | 60 +++++++++++++++++++++++++++++++++----------- >>>> 2 files changed, 48 insertions(+), 14 deletions(-) >>>> >>>> diff --git a/include/linux/rmap.h b/include/linux/rmap.h >>>> index b87d01660412..a3825ce81102 100644 >>>> --- a/include/linux/rmap.h >>>> +++ b/include/linux/rmap.h >>>> @@ -198,6 +198,8 @@ void folio_add_new_anon_rmap(struct folio *, struct vm_area_struct *, >>>> unsigned long address); >>>> void page_add_file_rmap(struct page *, struct vm_area_struct *, >>>> bool compound); >>>> +void folio_add_file_rmap_range(struct folio *, struct page *, unsigned int nr, >>>> + struct vm_area_struct *, bool compound); >>>> void page_remove_rmap(struct page *, struct vm_area_struct *, >>>> bool compound); >>>> >>>> diff --git a/mm/rmap.c b/mm/rmap.c >>>> index 4898e10c569a..a91906b28835 100644 >>>> --- a/mm/rmap.c >>>> +++ b/mm/rmap.c >>>> @@ -1301,31 +1301,39 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, >>>> } >>>> >>>> /** >>>> - * page_add_file_rmap - add pte mapping to a file page >>>> - * @page: the page to add the mapping to >>>> + * folio_add_file_rmap_range - add pte mapping to page range of a folio >>>> + * @folio: The folio to add the mapping to >>>> + * @page: The first page to add >>>> + * @nr_pages: The number of pages which will be mapped >>>> * @vma: the vm area in which the mapping is added >>>> * @compound: charge the page as compound or small page >>>> * >>>> + * The page range of folio is defined by [first_page, first_page + nr_pages) >>>> + * >>>> * The caller needs to hold the pte lock. >>>> */ >>>> -void page_add_file_rmap(struct page *page, struct vm_area_struct *vma, >>>> - bool compound) >>>> +void folio_add_file_rmap_range(struct folio *folio, struct page *page, >>>> + unsigned int nr_pages, struct vm_area_struct *vma, >>>> + bool compound) >>>> { >>>> - struct folio *folio = page_folio(page); >>>> atomic_t *mapped = &folio->_nr_pages_mapped; >>>> - int nr = 0, nr_pmdmapped = 0; >>>> - bool first; >>>> + unsigned int nr_pmdmapped = 0, first; >>>> + int nr = 0; >>>> >>>> - VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page); >>>> + VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio); >>>> >>>> /* Is page being mapped by PTE? Is this its first map to be added? */ >>>> if (likely(!compound)) { >>>> - first = atomic_inc_and_test(&page->_mapcount); >>>> - nr = first; >>>> - if (first && folio_test_large(folio)) { >>>> - nr = atomic_inc_return_relaxed(mapped); >>>> - nr = (nr < COMPOUND_MAPPED); >>>> - } >>>> + do { >>>> + first = atomic_inc_and_test(&page->_mapcount); >>>> + if (first && folio_test_large(folio)) { >>>> + first = atomic_inc_return_relaxed(mapped); >>>> + first = (nr < COMPOUND_MAPPED); >>> >>> This still contains the typo that Yin Fengwei spotted in the previous version: >>> https://lore.kernel.org/linux-mm/20230228213738.272178-1-willy@infradead.org/T/#m84673899e25bc31356093a1177941f2cc35e5da8 >>> >>> FYI, I'm seeing a perf regression of about 1% when compiling the kernel on >>> Ampere Altra (arm64) with this whole series on top of v6.3-rc1 (In a VM using >>> ext4 filesystem). Looks like instruction aborts are taking much longer and a >>> selection of syscalls are a bit slower. Still hunting down the root cause. Will >>> report once I have conclusive diagnosis. >> >> I'm sorry - I'm struggling to find the exact cause. But its spending over 2x the >> amount of time in the instruction abort handling code once patches 32-36 are >> included. Everything in the flame graph is just taking longer. Perhaps we are >> getting more instruction aborts somehow? I have the flamegraphs if anyone wants >> them - just shout and I'll email them separately. > Thanks a lot to Ryan for sharing the flamegraphs to me. I found the __do_fault() > is called with patch 32-36 while no __do_fault() just with first 31 patches. I > suspect the folio_add_file_rmap_range() missed some PTEs population. Please give > me few days to find the root cause and fix. Sorry for this. You're welcome. Give me a shout once you have a re-spin and I'll rerun the tests. > > > Regards > Yin, Fengwei > >> >>> >>> Thanks, >>> Ryan >>> >>> >>>> + } >>>> + >>>> + if (first) >>>> + nr++; >>>> + } while (page++, --nr_pages > 0); >>>> } else if (folio_test_pmd_mappable(folio)) { >>>> /* That test is redundant: it's for safety or to optimize out */ >>>> >>>> @@ -1354,6 +1362,30 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma, >>>> mlock_vma_folio(folio, vma, compound); >>>> } >>>> >>>> +/** >>>> + * page_add_file_rmap - add pte mapping to a file page >>>> + * @page: the page to add the mapping to >>>> + * @vma: the vm area in which the mapping is added >>>> + * @compound: charge the page as compound or small page >>>> + * >>>> + * The caller needs to hold the pte lock. >>>> + */ >>>> +void page_add_file_rmap(struct page *page, struct vm_area_struct *vma, >>>> + bool compound) >>>> +{ >>>> + struct folio *folio = page_folio(page); >>>> + unsigned int nr_pages; >>>> + >>>> + VM_WARN_ON_ONCE_PAGE(compound && !PageTransHuge(page), page); >>>> + >>>> + if (likely(!compound)) >>>> + nr_pages = 1; >>>> + else >>>> + nr_pages = folio_nr_pages(folio); >>>> + >>>> + folio_add_file_rmap_range(folio, page, nr_pages, vma, compound); >>>> +} >>>> + >>>> /** >>>> * page_remove_rmap - take down pte mapping from a page >>>> * @page: page to remove mapping from >>> >>