From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754576AbdCHVUr (ORCPT ); Wed, 8 Mar 2017 16:20:47 -0500 Received: from mga01.intel.com ([192.55.52.88]:11403 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754546AbdCHVUp (ORCPT ); Wed, 8 Mar 2017 16:20:45 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.36,265,1486454400"; d="scan'208";a="65566601" Message-ID: <1489001545.7212.61.camel@linux.intel.com> Subject: Re: [RFC][PATCH 0/4] tracing: Allow function tracing to start earlier in boot up From: Todd Brandt Reply-To: todd.e.brandt@linux.intel.com To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton Date: Wed, 08 Mar 2017 11:32:25 -0800 In-Reply-To: <1489000557.7212.58.camel@linux.intel.com> References: <20170307212833.964734229@goodmis.org> <1489000557.7212.58.camel@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11-0ubuntu3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2017-03-08 at 11:15 -0800, Todd Brandt wrote: > On Tue, 2017-03-07 at 16:28 -0500, Steven Rostedt wrote: > > I've had people ask about moving tracing up further in the boot process. > > This patch series looks at function tracing only. It allows for tracing > > (and function filtering) to be moved right after memory is initialized. > > To have it happen before memory initialization would require a bit more > > work with allocating the ring buffer. But this is a start. > > I just tested out the patch and it does move function trace up to about > 100ms from boot which is nice. What I'd really like is for graph trace > to start sooner as well. > > P.S. I've noticed that the dmesg log and ftrace log times don't seem to > match up anymore since the v10.0 release. Is the default still the local > clock? On v10.0-rc8 I was able to match initcall_debug output with > do_one_initcall function_graph trace perfectly. But the latest is off by > anywhere from several microseconds to several milliseconds. Did I just > get lucky with v10.0-rc8 or should these still align? > > v10.0-rc8 (ftrace time = dmesg time) > > FTRACE: > 0.519902 | 0) systemd-1 | | do_one_initcall() { > 0.519921 | 0) systemd-1 | | do_one_initcall() { > 0.519929 | 0) systemd-1 | | do_one_initcall() { > 0.519938 | 0) systemd-1 | | do_one_initcall() { > 0.519946 | 0) systemd-1 | | do_one_initcall() { > DMESG: > [ 0.519909] calling init_per_zone_wmark_min+0x0/0x73 @ 1 > [ 0.519925] calling init_zero_pfn+0x0/0x3d @ 1 > [ 0.519932] calling memory_failure_init+0x0/0xa4 @ 1 > [ 0.519941] calling cma_init_reserved_areas+0x0/0x1cd @ 1 > [ 0.519949] calling fsnotify_init+0x0/0x26 @ 1 > > v4.11-rc1 (ftrace = dmesg + 5.089 ms) > > FTRACE: > 0.445317 | 2) systemd-1 | | do_one_initcall() { > 0.445338 | 2) systemd-1 | | do_one_initcall() { > 0.445346 | 2) systemd-1 | | do_one_initcall() { > 0.445355 | 2) systemd-1 | | do_one_initcall() { > 0.445363 | 2) systemd-1 | | do_one_initcall() { > DMESG: > [ 0.440232] calling init_per_zone_wmark_min+0x0/0x73 @ 1 > [ 0.440249] calling init_zero_pfn+0x0/0x3d @ 1 > [ 0.440257] calling memory_failure_init+0x0/0xa4 @ 1 > [ 0.440266] calling cma_init_reserved_areas+0x0/0x1cd @ 1 > [ 0.440275] calling fsnotify_init+0x0/0x26 @ 1 Oops, no sooner than 5 minutes after I sent this did I figure out there's a trace_clock kernel parameter (not in kernel-parameters.txt). Once I set it to global all is well. Never mind :) > > > > > > I placed a hook into free_reserved_area() which is used by all archs > > to free the init memory. Having it pass the range being freed to ftrace > > lets ftrace clean up any function that is registered such that it doesn't > > try to modify code that no longer exists. > > > > > > Steven Rostedt (VMware) (4): > > tracing: Split tracing initialization into two for early initialization > > ftrace: Move ftrace_init() to right after memory initialization > > ftrace: Have function tracing start in early boot up > > ftrace: Allow for function tracing to record init functions on boot up > > > > ---- > > include/linux/ftrace.h | 5 +++++ > > include/linux/init.h | 4 +++- > > init/main.c | 9 ++++++--- > > kernel/trace/ftrace.c | 44 ++++++++++++++++++++++++++++++++++++++++++ > > kernel/trace/trace.c | 9 ++++++++- > > kernel/trace/trace.h | 2 ++ > > kernel/trace/trace_functions.c | 3 +-- > > mm/page_alloc.c | 4 ++++ > > scripts/recordmcount.c | 1 + > > scripts/recordmcount.pl | 1 + > > 10 files changed, 75 insertions(+), 7 deletions(-) >