From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by kanga.kvack.org (Postfix) with ESMTP id 8A1C06B71AD for ; Wed, 5 Sep 2018 02:24:32 -0400 (EDT) Received: by mail-pl1-f200.google.com with SMTP id v9-v6so3253581ply.13 for ; Tue, 04 Sep 2018 23:24:32 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id d35-v6si1024468pla.116.2018.09.04.23.24.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 04 Sep 2018 23:24:31 -0700 (PDT) Date: Wed, 5 Sep 2018 08:24:28 +0200 From: Michal Hocko Subject: Re: [PATCH 2/2] mm: Create non-atomic version of SetPageReserved for init use Message-ID: <20180905062428.GV14951@dhcp22.suse.cz> References: <20180904181550.4416.50701.stgit@localhost.localdomain> <20180904183345.4416.76515.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180904183345.4416.76515.stgit@localhost.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Alexander Duyck Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, alexander.h.duyck@intel.com, pavel.tatashin@microsoft.com, akpm@linux-foundation.org, mingo@kernel.org, kirill.shutemov@linux.intel.com On Tue 04-09-18 11:33:45, Alexander Duyck wrote: > 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. I agree with Dave about a comment is due. I am also quite surprised that this leads to such a large improvement. Could you be more specific about your test and machines you were testing on? Other than that the patch makes sense to me. > Signed-off-by: Alexander Duyck With the above addressed, feel free to add Acked-by: Michal Hocko Thanks! > --- > include/linux/page-flags.h | 1 + > mm/page_alloc.c | 4 ++-- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index 74bee8cecf4c..57ec3fef7e9f 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -292,6 +292,7 @@ static inline int PagePoisoned(const struct page *page) > > 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 05e983f42316..9c7d6e971630 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1231,7 +1231,7 @@ void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end) > /* Avoid false-positive PageTail() */ > INIT_LIST_HEAD(&page->lru); > > - SetPageReserved(page); > + __SetPageReserved(page); > } > } > } > @@ -5518,7 +5518,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, > page = pfn_to_page(pfn); > __init_single_page(page, pfn, zone, nid); > if (context == MEMMAP_HOTPLUG) > - SetPageReserved(page); > + __SetPageReserved(page); > > /* > * Mark the block movable so that blocks are reserved for > -- Michal Hocko SUSE Labs