From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx152.postini.com [74.125.245.152]) by kanga.kvack.org (Postfix) with SMTP id CC6C66B0269 for ; Fri, 22 Jun 2012 17:47:16 -0400 (EDT) Date: Fri, 22 Jun 2012 14:47:14 -0700 From: Andrew Morton Subject: Re: [PATCH -mm v2 00/11] mm: scalable and unified arch_get_unmapped_area Message-Id: <20120622144714.440f8529.akpm@linux-foundation.org> In-Reply-To: <20452.32826.165122.958868@quad.stoffel.home> References: <1340315835-28571-1-git-send-email-riel@surriel.com> <20452.32826.165122.958868@quad.stoffel.home> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: John Stoffel Cc: Rik van Riel , linux-mm@kvack.org, aarcange@redhat.com, peterz@infradead.org, minchan@gmail.com, kosaki.motohiro@gmail.com, andi@firstfloor.org, hannes@cmpxchg.org, mel@csn.ul.ie, linux-kernel@vger.kernel.org On Fri, 22 Jun 2012 10:24:58 -0400 "John Stoffel" wrote: > >>>>> "Rik" == Rik van Riel writes: > > Rik> A long time ago, we decided to limit the number of VMAs per > Rik> process to 64k. As it turns out, there actually are programs > Rik> using tens of thousands of VMAs. > > > Rik> Performance > > Rik> Testing performance with a benchmark that allocates tens > Rik> of thousands of VMAs, unmaps them and mmaps them some more > Rik> in a loop, shows promising results. > > How are the numbers for applications which only map a few VMAs? Is > there any impact there? > Johannes did a test for that: https://lkml.org/lkml/2012/6/22/219 Some regression with such a workload is unavoidable, I expect. We have to work out whether the pros outweigh the cons. This involves handwaving. -- 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