From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 5 Apr 2007 21:11:29 +0200 From: Ingo Molnar Subject: Re: preemption and rwsems (was: Re: missing madvise functionality) Message-ID: <20070405191129.GC22092@elte.hu> References: <20070404160006.8d81a533.akpm@linux-foundation.org> <46128051.9000609@redhat.com> <46128CC2.9090809@redhat.com> <20070403172841.GB23689@one.firstfloor.org> <20070403125903.3e8577f4.akpm@linux-foundation.org> <4612B645.7030902@redhat.com> <20070403202937.GE355@devserv.devel.redhat.com> <19526.1175777338@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <19526.1175777338@redhat.com> Sender: owner-linux-mm@kvack.org Return-Path: To: David Howells Cc: Andrew Morton , Jakub Jelinek , Ulrich Drepper , Andi Kleen , Rik van Riel , Linux Kernel , linux-mm@kvack.org, Hugh Dickins List-ID: * David Howells wrote: > But short of recording the lock sequence, I don't think there's anyway > to find out for sure. printk probably won't cut it as a recording > mechanism because its overheads are too great. getting a good trace of it is easy: pick up the latest -rt kernel from: http://redhat.com/~mingo/realtime-preempt/ enable EVENT_TRACING in that kernel, run the workload and do: scripts/trace-it > to-ingo.txt and send me the output. It will be large but interesting. That should get us a whole lot closer to what happens. A (much!) more finegrained result would be to also enable FUNCTION_TRACING and to do: echo 1 > /proc/sys/kernel/mcount_enabled before running trace-it. Ingo -- 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