From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id D773D6B0007 for ; Wed, 11 Jul 2018 12:47:33 -0400 (EDT) Received: by mail-qk0-f199.google.com with SMTP id c27-v6so29832930qkj.3 for ; Wed, 11 Jul 2018 09:47:33 -0700 (PDT) Received: from userp2130.oracle.com (userp2130.oracle.com. [156.151.31.86]) by mx.google.com with ESMTPS id x9-v6si1567244qka.303.2018.07.11.09.47.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Jul 2018 09:47:32 -0700 (PDT) Subject: Re: [PATCH] mm: hugetlb: don't zero 1GiB bootmem pages. References: <20180710184903.68239-1-cannonmatthews@google.com> <20180711124711.GA20172@dhcp22.suse.cz> <20180711124801.GO20050@dhcp22.suse.cz> From: Mike Kravetz Message-ID: <3f639e81-f8d2-5010-4a4b-331d198b1ce9@oracle.com> Date: Wed, 11 Jul 2018 09:47:25 -0700 MIME-Version: 1.0 In-Reply-To: <20180711124801.GO20050@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Cannon Matthews Cc: Andrew Morton , Nadia Yvette Chambers , linux-mm@kvack.org, linux-kernel@vger.kernel.org, andreslc@google.com, pfeiner@google.com, dmatlack@google.com, gthelen@google.com On 07/11/2018 05:48 AM, Michal Hocko wrote: > On Wed 11-07-18 14:47:11, Michal Hocko wrote: >> On Tue 10-07-18 11:49:03, Cannon Matthews wrote: >>> When using 1GiB pages during early boot, use the new >>> memblock_virt_alloc_try_nid_raw() function to allocate memory without >>> zeroing it. Zeroing out hundreds or thousands of GiB in a single core >>> memset() call is very slow, and can make early boot last upwards of >>> 20-30 minutes on multi TiB machines. >>> >>> To be safe, still zero the first sizeof(struct boomem_huge_page) bytes >>> since this is used a temporary storage place for this info until >>> gather_bootmem_prealloc() processes them later. >>> >>> The rest of the memory does not need to be zero'd as the hugetlb pages >>> are always zero'd on page fault. >>> >>> Tested: Booted with ~3800 1G pages, and it booted successfully in >>> roughly the same amount of time as with 0, as opposed to the 25+ >>> minutes it would take before. >> >> The patch makes perfect sense to me. I wasn't even aware that it >> zeroying memblock allocation. Thanks for spotting this and fixing it. >> >>> Signed-off-by: Cannon Matthews >> >> I just do not think we need to to zero huge_bootmem_page portion of it. >> It should be sufficient to INIT_LIST_HEAD before list_add. We do >> initialize the rest explicitly already. > > Forgot to mention that after that is addressed you can add > Acked-by: Michal Hocko Cannon, How about if you make this change suggested by Michal, and I will submit a separate patch to revert the patch which added the phys field to huge_bootmem_page structure. FWIW, Reviewed-by: Mike Kravetz -- Mike Kravetz