Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941314AbcKXUV0 (ORCPT ); Thu, 24 Nov 2016 15:21:26 -0500 Received: from mail-pg0-f41.google.com ([74.125.83.41]:33341 "EHLO mail-pg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933168AbcKXUVU (ORCPT ); Thu, 24 Nov 2016 15:21:20 -0500 From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: Joel Fernandes , Steven Rostedt , Thomas Gleixner , John Stultz , Ingo Molnar , Jonathan Corbet , linux-doc@vger.kernel.org (open list:DOCUMENTATION) Subject: [PATCH v3 3/3] trace: Update documentation for mono, mono_raw and boot clock Date: Thu, 24 Nov 2016 12:20:51 -0800 Message-Id: <1480018851-3796-4-git-send-email-joelaf@google.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 In-Reply-To: <1480018851-3796-1-git-send-email-joelaf@google.com> References: <1480018851-3796-1-git-send-email-joelaf@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1892 Lines: 45 Documentation was missing for mono and mono_raw, add them and also for the boot clock introduced in this series. Cc: Steven Rostedt Cc: Thomas Gleixner Cc: John Stultz Cc: Ingo Molnar Signed-off-by: Joel Fernandes --- Documentation/trace/ftrace.txt | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 185c39f..5180b09 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -362,6 +362,26 @@ of ftrace. Here is a list of some of the key files: to correlate events across hypervisor/guest if tb_offset is known. + mono: This uses the fast monotonic clock (CLOCK_MONOTONIC) + which is monotonic and is subject to NTP rate adjustments. + + mono_raw: + This is the raw monotonic clock (CLOCK_MONOTONIC_RAW) + which is montonic but is not subject to any rate adjustments + and ticks at the same rate as the hardware clocksource. + + boot: This is the boot clock (CLOCK_BOOTTIME) and is based on the + fast monotonic clock, but also accounts for time spent in + suspend. Since the clock access is designed for use in + tracing in the suspend path, some side effects are possible + if clock is accessed after the suspend time is accounted before + the fast mono clock is updated. In this case, the clock update + appears to happen slightly sooner than it normally would have. + Also on 32-bit systems, its possible that the 64-bit boot offset + sees a partial update. These effects are rare and post + processing should be able to handle them. See comments on + ktime_get_boot_fast_ns function for more information. + To set a clock, simply echo the clock name into this file. echo global > trace_clock -- 2.8.0.rc3.226.g39d4020