From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx168.postini.com [74.125.245.168]) by kanga.kvack.org (Postfix) with SMTP id 573D86B005D for ; Fri, 4 Jan 2013 10:01:43 -0500 (EST) Received: by mail-qc0-f177.google.com with SMTP id u28so8668998qcs.22 for ; Fri, 04 Jan 2013 07:01:42 -0800 (PST) Date: Fri, 4 Jan 2013 10:01:39 -0500 From: Tejun Heo Subject: Re: [RFC PATCH] mm: memblock: optimize memblock_find_in_range_node() to minimize the search work Message-ID: <20130104150139.GB15633@mtj.dyndns.org> References: <1357291493-25773-1-git-send-email-linfeng@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1357291493-25773-1-git-send-email-linfeng@cn.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: Lin Feng Cc: akpm@linux-foundation.org, mingo@kernel.org, yinghai@kernel.org, liwanp@linux.vnet.ibm.com, benh@kernel.crashing.org, tangchen@cn.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Fri, Jan 04, 2013 at 05:24:53PM +0800, Lin Feng wrote: > The memblock array is in ascending order and we traverse the memblock array in > reverse order so we can add some simple check to reduce the search work. > > Tejun fix a underflow bug in 5d53cb27d8, but I think we could break there for > the same reason. > > Cc: Tejun Heo > Signed-off-by: Lin Feng > --- > mm/memblock.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 6259055..a710557 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -111,11 +111,18 @@ phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t start, > end = max(start, end); > > for_each_free_mem_range_reverse(i, nid, &this_start, &this_end, NULL) { > + /* > + * exclude the regions out of the candidate range, since it's > + * likely to find a suitable range, we ignore the worst case. > + */ > + if (this_start >= end) > + continue; > + > this_start = clamp(this_start, start, end); > this_end = clamp(this_end, start, end); > > if (this_end < size) > - continue; > + break; I don't know. This only saves looping when memblocks are below the requested size, right? I don't think it would matter in any way and would prefer to keep the logic as simple as possible. Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org