From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 08A4D6005A4 for ; Tue, 5 Jan 2010 01:24:46 -0500 (EST) Received: by pxi5 with SMTP id 5so11172004pxi.12 for ; Mon, 04 Jan 2010 22:24:45 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20100105150932.ab2e6820.kamezawa.hiroyu@jp.fujitsu.com> References: <20100104182429.833180340@chello.nl> <20100104182813.753545361@chello.nl> <20100105092559.1de8b613.kamezawa.hiroyu@jp.fujitsu.com> <28c262361001042029w4b95f226lf54a3ed6a4291a3b@mail.gmail.com> <28c262361001042209k7241dd38l3d51d230e7b68a5@mail.gmail.com> <20100105150932.ab2e6820.kamezawa.hiroyu@jp.fujitsu.com> Date: Tue, 5 Jan 2010 15:24:45 +0900 Message-ID: <28c262361001042224u44bad2e8r8eafdbdff673076a@mail.gmail.com> Subject: Re: [RFC][PATCH 6/8] mm: handle_speculative_fault() From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Linus Torvalds , Peter Zijlstra , "Paul E. McKenney" , Peter Zijlstra , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , cl@linux-foundation.org, "hugh.dickins" , Nick Piggin , Ingo Molnar List-ID: On Tue, Jan 5, 2010 at 3:09 PM, KAMEZAWA Hiroyuki wrote: > On Tue, 5 Jan 2010 15:09:47 +0900 > Minchan Kim wrote: >> My humble opinion is following as. >> >> Couldn't we synchronize rcu in that cases(munmap, exit and so on)? >> It can delay munap and exit but it would be better than handling them by more >> complicated things, I think. And both cases aren't often cases so we >> can achieve advantage than disadvantage? >> > > In most case, a program is single threaded. And sychronize_rcu() in unmap path > just adds very big overhead. Yes. I suggested you that consider single-thread app's regression, please. :) First I come to my head is we can count number of thread. Yes. thread number is a not good choice. As a matter of fact, I want to work it adaptively. If the process start to have many threads, speculative page fault turn on or turn off. I know it's not easy. I hope other guys have good ideas. > > Thanks, > -Kame > > -- Kind regards, Minchan Kim -- 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