From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) by kanga.kvack.org (Postfix) with ESMTP id C92A18E0001 for ; Mon, 10 Sep 2018 19:43:50 -0400 (EDT) Received: by mail-pg1-f199.google.com with SMTP id f13-v6so11374655pgs.15 for ; Mon, 10 Sep 2018 16:43:50 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id t8-v6sor3072510plz.147.2018.09.10.16.43.49 for (Google Transport Security); Mon, 10 Sep 2018 16:43:49 -0700 (PDT) Subject: [PATCH 2/4] mm: Create non-atomic version of SetPageReserved for init use From: Alexander Duyck Date: Mon, 10 Sep 2018 16:43:48 -0700 Message-ID: <20180910234348.4068.92164.stgit@localhost.localdomain> In-Reply-To: <20180910232615.4068.29155.stgit@localhost.localdomain> References: <20180910232615.4068.29155.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org Cc: pavel.tatashin@microsoft.com, mhocko@suse.com, dave.jiang@intel.com, mingo@kernel.org, dave.hansen@intel.com, jglisse@redhat.com, akpm@linux-foundation.org, logang@deltatee.com, dan.j.williams@intel.com, kirill.shutemov@linux.intel.com From: Alexander Duyck It doesn't make much sense to use the atomic SetPageReserved at init time when we are using memset to clear the memory and manipulating the page flags via simple "&=" and "|=" operations in __init_single_page. This patch adds a non-atomic version __SetPageReserved that can be used during page init and shows about a 10% improvement in initialization times on the systems I have available for testing. On those systems I saw initialization times drop from around 35 seconds to around 32 seconds to initialize a 3TB block of persistent memory. I tried adding a bit of documentation based on commit ("mm, memory_hotplug: do not associate hotadded memory to zones until online"). Ideally the reserved flag should be set earlier since there is a brief window where the page is initialization via __init_single_page and we have not set the PG_Reserved flag. I'm leaving that for a future patch set as that will require a more significant refactor. Acked-by: Michal Hocko Signed-off-by: Alexander Duyck --- include/linux/page-flags.h | 1 + mm/page_alloc.c | 17 +++++++++++++++-- 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index d00216cf00f8..1b1f8e0378ae 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -300,6 +300,7 @@ static inline void page_init_poison(struct page *page, size_t size) PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) + __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 89d2a2ab3fe6..a9b095a72fd9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1231,7 +1231,12 @@ void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end) /* Avoid false-positive PageTail() */ INIT_LIST_HEAD(&page->lru); - SetPageReserved(page); + /* + * no need for atomic set_bit because the struct + * page is not visible yet so nobody should + * access it yet. + */ + __SetPageReserved(page); } } } @@ -5517,8 +5522,16 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, not_early: page = pfn_to_page(pfn); __init_single_page(page, pfn, zone, nid); + + /* + * Mark page reserved as it will need to wait for onlining + * phase for it to be fully associated with a zone. + * + * We can use the non-atomic __set_bit operation for setting + * the flag as we are still initializing the pages. + */ if (context == MEMMAP_HOTPLUG) - SetPageReserved(page); + __SetPageReserved(page); /* * Mark the block movable so that blocks are reserved for