From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Subject: Re: [PATCH 2/2] tracing: syscall_regfunc() should not skip kernel threads Date: Mon, 18 Mar 2013 17:26:50 +0100 Message-ID: <20130318162650.GA20313@redhat.com> References: <20130317182834.GA22989@redhat.com> <1363546493.25967.129.camel@gandalf.local.home> <20130317190438.GA24582@redhat.com> <1363548972.25967.137.camel@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1363548972.25967.137.camel@gandalf.local.home> Sender: linux-kernel-owner@vger.kernel.org To: Steven Rostedt Cc: Andrew Morton , Ingo Molnar , Frederic Weisbecker , linux-kernel@vger.kernel.org, "H. Peter Anvin" , linux-arch List-Id: linux-arch.vger.kernel.org On 03/17, Steven Rostedt wrote: > > On Sun, 2013-03-17 at 20:04 +0100, Oleg Nesterov wrote: > > > > I'm really thinking the TIF_SYSCALL_TRACEPOINT flag is getting a bit > > > ridiculous. We really should have a "swap syscall table when tracepoints > > > enabled" that changes the syscall table that does exactly the same thing > > > as the normal table but wraps the system call with the tracepoints. > > > > But we also need to force the slow path in system_call... > > Why? If we remove the tracepoint from the slowpath and use a table swap, > then we wouldn't need to use the slowpath at all. Ah, indeed, you are right. > > Anyway, do you agree with this change for now? > > Well, if it's solving a bug today sure. But we should really be looking > at fixing what's there for the future. OK, thanks. Oleg. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:27058 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751431Ab3CRQ3C (ORCPT ); Mon, 18 Mar 2013 12:29:02 -0400 Date: Mon, 18 Mar 2013 17:26:50 +0100 From: Oleg Nesterov Subject: Re: [PATCH 2/2] tracing: syscall_regfunc() should not skip kernel threads Message-ID: <20130318162650.GA20313@redhat.com> References: <20130317182834.GA22989@redhat.com> <1363546493.25967.129.camel@gandalf.local.home> <20130317190438.GA24582@redhat.com> <1363548972.25967.137.camel@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1363548972.25967.137.camel@gandalf.local.home> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Steven Rostedt Cc: Andrew Morton , Ingo Molnar , Frederic Weisbecker , linux-kernel@vger.kernel.org, "H. Peter Anvin" , linux-arch Message-ID: <20130318162650.-RcYGTt4rwQylxsItvw6DdGDz8v2yIu0kJbEU0kAUa0@z> On 03/17, Steven Rostedt wrote: > > On Sun, 2013-03-17 at 20:04 +0100, Oleg Nesterov wrote: > > > > I'm really thinking the TIF_SYSCALL_TRACEPOINT flag is getting a bit > > > ridiculous. We really should have a "swap syscall table when tracepoints > > > enabled" that changes the syscall table that does exactly the same thing > > > as the normal table but wraps the system call with the tracepoints. > > > > But we also need to force the slow path in system_call... > > Why? If we remove the tracepoint from the slowpath and use a table swap, > then we wouldn't need to use the slowpath at all. Ah, indeed, you are right. > > Anyway, do you agree with this change for now? > > Well, if it's solving a bug today sure. But we should really be looking > at fixing what's there for the future. OK, thanks. Oleg.