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 650AF6B0003 for ; Wed, 31 Oct 2018 12:05:07 -0400 (EDT) Received: by mail-pg1-f199.google.com with SMTP id m21-v6so9051689pgl.16 for ; Wed, 31 Oct 2018 09:05:07 -0700 (PDT) Received: from mga17.intel.com (mga17.intel.com. [192.55.52.151]) by mx.google.com with ESMTPS id f65-v6si28362447pff.276.2018.10.31.09.05.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Oct 2018 09:05:05 -0700 (PDT) Message-ID: Subject: Re: [mm PATCH v4 3/6] mm: Use memblock/zone specific iterator for handling deferred page init From: Alexander Duyck Date: Wed, 31 Oct 2018 09:05:04 -0700 In-Reply-To: <5b937f29-a6e1-6622-b035-246229021d3e@microsoft.com> References: <20181017235043.17213.92459.stgit@localhost.localdomain> <20181017235419.17213.68425.stgit@localhost.localdomain> <5b937f29-a6e1-6622-b035-246229021d3e@microsoft.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Pasha Tatashin , "linux-mm@kvack.org" , "akpm@linux-foundation.org" Cc: "mhocko@suse.com" , "dave.jiang@intel.com" , "linux-kernel@vger.kernel.org" , "willy@infradead.org" , "davem@davemloft.net" , "yi.z.zhang@linux.intel.com" , "khalid.aziz@oracle.com" , "rppt@linux.vnet.ibm.com" , "vbabka@suse.cz" , "sparclinux@vger.kernel.org" , "dan.j.williams@intel.com" , "ldufour@linux.vnet.ibm.com" , "mgorman@techsingularity.net" , "mingo@kernel.org" , "kirill.shutemov@linux.intel.com" On Wed, 2018-10-31 at 15:40 +0000, Pasha Tatashin wrote: > > On 10/17/18 7:54 PM, Alexander Duyck wrote: > > This patch introduces a new iterator for_each_free_mem_pfn_range_in_zone. > > > > This iterator will take care of making sure a given memory range provided > > is in fact contained within a zone. It takes are of all the bounds checking > > we were doing in deferred_grow_zone, and deferred_init_memmap. In addition > > it should help to speed up the search a bit by iterating until the end of a > > range is greater than the start of the zone pfn range, and will exit > > completely if the start is beyond the end of the zone. > > > > This patch adds yet another iterator called > > for_each_free_mem_range_in_zone_from and then uses it to support > > initializing and freeing pages in groups no larger than MAX_ORDER_NR_PAGES. > > By doing this we can greatly improve the cache locality of the pages while > > we do several loops over them in the init and freeing process. > > > > We are able to tighten the loops as a result since we only really need the > > checks for first_init_pfn in our first iteration and after that we can > > assume that all future values will be greater than this. So I have added a > > function called deferred_init_mem_pfn_range_in_zone that primes the > > iterators and if it fails we can just exit. > > > > On my x86_64 test system with 384GB of memory per node I saw a reduction in > > initialization time from 1.85s to 1.38s as a result of this patch. > > > > Signed-off-by: Alexander Duyck > > Hi Alex, > > Could you please split this patch into two parts: > > 1. Add deferred_init_maxorder() > 2. Add memblock iterator? > > This would allow a better bisecting in case of problems. Chaning two > loops into deferred_init_maxorder() while a good idea, is still > non-trivial and might lead to bugs. > > Thank you, > Pavel I can do that, but I will need to flip the order. I will add the new iterator first and then deferred_init_maxorder. Otherwise the intermediate step ends up being too much throw-away code. - Alex