Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753252AbdLNUtq (ORCPT ); Thu, 14 Dec 2017 15:49:46 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:35195 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752377AbdLNUtp (ORCPT ); Thu, 14 Dec 2017 15:49:45 -0500 Date: Thu, 14 Dec 2017 21:49:32 +0100 From: Peter Zijlstra To: Teng Qin Cc: mingo@redhat.com, ast@fb.com, bgregg@netflix.com, daniel@iogearbox.net, yhs@fb.com, linux-kernel@vger.kernel.org, Kernel-team@fb.com Subject: Re: [PATCH tip 0/3] Improvements of scheduler related Tracepoints Message-ID: <20171214204932.GH3326@worktop> References: <20171214202044.1629279-1-qinteng@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171214202044.1629279-1-qinteng@fb.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1007 Lines: 20 On Thu, Dec 14, 2017 at 12:20:41PM -0800, Teng Qin wrote: > This set of commits attempts to improve three scheduler related > Tracepoints: sched_switch, sched_process_fork, sched_process_exit. > > Firstly, these commit add additional flag values, namely preempt, > clone_flags and group_dead to these Tracepoints, to make information > exposed via the Tracepoints more useful and complete. > > Secondly, these commits exposes task_struct pointers in these > Tracepoints. The task_struct pointers are arguments of the Tracepoints > and currently only used to compute struct field values. But for BPF > programs attached to these Tracepoints, we may want to read additional > task information via the task_struct pointers. This is currently either > impossible, or we have to make assumption of whether the Tracepoint is > running from previous / parent or next / child, and use current pointer > instead. Exposing the task_struct pointers explicitly makes such use > case easier and more reliable. > NAK