From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757458AbYECNYa (ORCPT ); Sat, 3 May 2008 09:24:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754800AbYECNYV (ORCPT ); Sat, 3 May 2008 09:24:21 -0400 Received: from mx1.redhat.com ([66.187.233.31]:47183 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752582AbYECNYU (ORCPT ); Sat, 3 May 2008 09:24:20 -0400 Date: Sat, 3 May 2008 09:23:27 -0400 From: "Frank Ch. Eigler" To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Subject: preempt-rt, need old style rwlocks for systemtap Message-ID: <20080503132327.GA28881@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi - It has come to my attention that the preempt-rt patch suite deliberately defeats the potential concurrency intended by systemtap's use of rwlocks to permit concurrent readers of various data structures. Since systemtap's probe handlers are all atomic, nonblocking, nonpreemptable, it does not seem like there is any real-time-oriented benefit in this. What can we do to work around this and permit reader concurrency again in preempt-rt? - FChE