From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3D6E9084.820B2608@zip.com.au> Date: Thu, 29 Aug 2002 14:22:12 -0700 From: Andrew Morton MIME-Version: 1.0 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: owner-linux-mm@kvack.org Return-Path: To: Robert Love Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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, 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/