platform_system_core/init/bootchart.h
Bo (Andover) Zhang 3700373c67 Fixed the pacing logic in bootchart data collection.
Ideally bootchart collects system data every BOOTCHART_POLLING_MS ms.
However, the current bootchart pacing logic would collect data every
time the main loop in init.c is executed. This results in:

1. Multiple data samples being taken consecutively or prematurely. In
many cases, these data samples have the same timestamp (in jiffies).
The off-line data processing tool would complain about dividing by
zero "interval" and bail out.

2. Because of the ineffective pacing, bootchart data collection would
terminate prematurely. The total duration of data collection is usually
much shorter than what the user specifies.

The fix is to check whether BOOTCHART_POLLING_MS ms has elapsed
before taking a new data sample. For this purpose, /proc/uptime
is used to get the time values, consistent with the precision of
bootchart timestamps.

Change-Id: I106bf91dbda01059b719df6c73b8bd1cd54a64f0
Signed-off-by: Bo (Andover) Zhang <zhang@broadcom.com>
2014-07-29 21:09:01 -04:00

37 lines
1.1 KiB
C

/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef _BOOTCHART_H
#define _BOOTCHART_H
#ifndef BOOTCHART
# define BOOTCHART 0
#endif
#if BOOTCHART
extern int bootchart_init(void);
extern int bootchart_step(void);
extern void bootchart_finish(void);
extern long long bootchart_gettime(void);
# define BOOTCHART_POLLING_MS 200 /* polling period in ms */
# define BOOTCHART_DEFAULT_TIME_SEC (2*60) /* default polling time in seconds */
# define BOOTCHART_MAX_TIME_SEC (10*60) /* max polling time in seconds */
#endif /* BOOTCHART */
#endif /* _BOOTCHART_H */