Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 29 Aug 2002 17:19:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 29 Aug 2002 17:19:51 -0400 Received: from vasquez.zip.com.au ([203.12.97.41]:34834 "EHLO vasquez.zip.com.au") by vger.kernel.org with ESMTP id ; Thu, 29 Aug 2002 17:19:50 -0400 Message-ID: <3D6E9084.820B2608@zip.com.au> Date: Thu, 29 Aug 2002 14:22:12 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-rc3 i686) X-Accept-Language: en MIME-Version: 1.0 To: Robert Love CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] low-latency zap_page_range() References: <3D6E8B7F.8D5D20D8@zip.com.au> <1030655532.12110.2691.camel@phantasy> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 970 Lines: 24 Robert Love wrote: > > On Thu, 2002-08-29 at 17:00, Andrew Morton wrote: > > > That's an interesting point. page_table_lock is one of those locks > > which is occasionally held for ages, and frequently held for a short > > time. > > Since latency is a direct function of lock held times in the preemptible > kernel, and I am seeing disgusting zap_page_range() latencies, the lock > is held a long time. > > So we know it is held forever and a day... but is there contention? I'm sure there is, but nobody has measured the right workload. Two CLONE_MM threads, one running mmap()/munmap(), the other trying to fault in some pages. I'm sure someone has some vital application which does exactly this. They always do :( - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/