From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx197.postini.com [74.125.245.197]) by kanga.kvack.org (Postfix) with SMTP id E8B406B00A9 for ; Mon, 16 Jan 2012 13:22:24 -0500 (EST) Received: from /spool/local by e5.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 16 Jan 2012 13:22:23 -0500 Received: from d01relay01.pok.ibm.com (d01relay01.pok.ibm.com [9.56.227.233]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 40ACA6EB836 for ; Mon, 16 Jan 2012 11:50:38 -0500 (EST) Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay01.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q0GGobgG274774 for ; Mon, 16 Jan 2012 11:50:37 -0500 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q0GGoRa2009855 for ; Mon, 16 Jan 2012 14:50:37 -0200 Date: Mon, 16 Jan 2012 22:11:46 +0530 From: Srikar Dronamraju Subject: Re: [PATCH v9 3.2 7/9] tracing: uprobes trace_event interface Message-ID: <20120116164146.GI10189@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20120110114821.17610.9188.sendpatchset@srdronam.in.ibm.com> <20120110114943.17610.28293.sendpatchset@srdronam.in.ibm.com> <20120116131137.GB5265@m.brq.redhat.com> <20120116144538.GG10189@linux.vnet.ibm.com> <20120116153327.GE5265@m.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20120116153327.GE5265@m.brq.redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jiri Olsa Cc: Peter Zijlstra , Linus Torvalds , Oleg Nesterov , Ingo Molnar , Andrew Morton , LKML , Linux-mm , Andi Kleen , Christoph Hellwig , Steven Rostedt , Roland McGrath , Thomas Gleixner , Masami Hiramatsu , Arnaldo Carvalho de Melo , Anton Arapov , Ananth N Mavinakayanahalli , Jim Keniston , Stephen Rothwell * Jiri Olsa [2012-01-16 16:33:27]: > On Mon, Jan 16, 2012 at 08:15:38PM +0530, Srikar Dronamraju wrote: > > > > > > I've tested following event: > > > echo "p:probe_libc/free /lib64/libc-2.13.so:0x7a4f0 %ax" > ./uprobe_events > > > > > > and commands like: > > > perf record -a -e probe_libc:free --filter "common_pid == 1127" > > > perf record -e probe_libc:free --filter "arg1 == 0xa" ls > > > > > > got me proper results. > > > > > > > Okay thanks for the inputs. > > > > > thanks, > > > jirka > > > > > > --- > > > The preemption needs to be disabled when submitting data into perf. > > > > I actually looked at other places where perf_trace_buf_prepare and > > perf_trace_buf_submit are being called. for example perf_syscall_enter > > and perf_syscall_exit both call the above routines and they didnt seem > > to be called with premption disabled. Is that the way perf probe is > > called in our case that needs us to call pre-emption here? Did you see a > > case where calling these without preemption disabled caused a problem? > > the perf_trace_buf_prepare touches per cpu variables, > hence the preemption disabling > > the perf_trace_buf_prepare code is used by syscalls, > kprobes, and trace events > > - both syscalls and trace events are implemented by > tracepoints which disable preemption before calling the probe > (see __DO_TRACE macro in include/linux/tracepoint.h) > > - kprobes disable preemption as well > (kprobe_handler in arch/x86/kernel/kprobes.c) > haven't checked the optimalized kprobes, > but should be the same case > > jirka > Okay, thanks for the clarification, I will pick the fix. -- Thanks and Regards Srikar -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org