From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5219 invoked by alias); 31 Mar 2006 14:07:59 -0000 Received: (qmail 5201 invoked by uid 22791); 31 Mar 2006 14:07:56 -0000 X-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 31 Mar 2006 14:07:53 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id k2VE7pGI019655; Fri, 31 Mar 2006 09:07:51 -0500 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [172.16.52.156]) by int-mx1.corp.redhat.com (8.12.11.20060308/8.11.6) with ESMTP id k2VE7pRC020870; Fri, 31 Mar 2006 09:07:51 -0500 Received: from [172.16.59.118] (dhcp59-118.rdu.redhat.com [172.16.59.118]) by pobox.corp.redhat.com (8.12.8/8.12.8) with ESMTP id k2VE7pxU001135; Fri, 31 Mar 2006 09:07:51 -0500 Message-ID: <442D37B6.8000009@redhat.com> Date: Fri, 31 Mar 2006 14:07:00 -0000 From: William Cohen User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Stone, Joshua I" CC: Roland McGrath , SystemTap Subject: Re: SystemTap vs. FC5 Xen kernels (was: 03-23-2006 Meeting minutes) References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q1/txt/msg00910.txt.bz2 Stone, Joshua I wrote: > William Cohen wrote: > >>Sometimes the options are turned off on purpose. Do the Xen kernels >>build with "CONFIG_KPROBES=y"? > > > yes > > >>If kernels are built, do the resulting kernels actually have kprobe >>support? It use to be that xen kernels copy and pasted code from other >>arches. What additional patches are needed to bring the kprobe support >>in the xen kernel in line with the various architectures? > > > > In order to get the debug info working, I removed the change to > lib/Kconfig.debug (mentioned in my other email), but left the change in > arch/x86_64/kernel/entry-xen.S. I suspect that more will need to be > done here before CONFIG_DEBUG_INFO really works completely, as there's > probably some reason it was disabled, but this is good enough for > testing SystemTap. > > On both xen0 and xenU, all pass-5 tests succeed, except those that use > timer.profile. (systemtap.base/timers.stp and > systemtap.maps/pmap_agg_overflow.stp). It seems that the timer.profile > thinks it is registered successfully, but the callback is never > triggered. I will investigate this further... > > > Josh Josh, The pass-5 tests working on xen is very good news. On the earlier s390 kernels the regular timer interrupt was eliminated. This was done for efficiency. The s390 has had virtualization for years. Having the Linux kernels do the timer interrupt was unwanted overhead. I wonder if the xen kernel is doing the same, only have timer interrupt when something really needs to get run at a certain time. http://lwn.net/Articles/138969/ Do we need variations on the timer probe, wall clock time and virtual time? -Will