From 3700373c67d08a4f180390cdd99b162e9ff0cfd3 Mon Sep 17 00:00:00 2001 From: "Bo (Andover) Zhang" Date: Thu, 24 Jul 2014 13:11:35 -0400 Subject: [PATCH] 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 --- init/bootchart.c | 37 ++++++++++++++++++++++--------------- init/bootchart.h | 1 + init/init.c | 29 ++++++++++++++++++++++++----- 3 files changed, 47 insertions(+), 20 deletions(-) diff --git a/init/bootchart.c b/init/bootchart.c index f72fcaaca..a514261f3 100644 --- a/init/bootchart.c +++ b/init/bootchart.c @@ -119,6 +119,18 @@ file_buff_done( FileBuff buff ) } } +static long long +get_uptime_jiffies() +{ + char buff[64]; + long long jiffies = 0; + + if (proc_read("/proc/uptime", buff, sizeof(buff)) > 0) + jiffies = 100LL*strtod(buff,NULL); + + return jiffies; +} + static void log_header(void) { @@ -185,22 +197,11 @@ static void do_log_uptime(FileBuff log) { char buff[65]; - int fd, ret, len; + int len; - fd = open("/proc/uptime",O_RDONLY); - if (fd >= 0) { - int ret; - ret = unix_read(fd, buff, 64); - close(fd); - buff[64] = 0; - if (ret >= 0) { - long long jiffies = 100LL*strtod(buff,NULL); - int len; - snprintf(buff,sizeof(buff),"%lld\n",jiffies); - len = strlen(buff); - file_buff_write(log, buff, len); - } - } + snprintf(buff,sizeof(buff),"%lld\n",get_uptime_jiffies()); + len = strlen(buff); + file_buff_write(log, buff, len); } static void @@ -376,3 +377,9 @@ void bootchart_finish( void ) file_buff_done(log_procs); acct(NULL); } + +/* called to get time (in ms) used by bootchart */ +long long bootchart_gettime( void ) +{ + return 10LL*get_uptime_jiffies(); +} diff --git a/init/bootchart.h b/init/bootchart.h index 39d2d4f20..ed65e8a9d 100644 --- a/init/bootchart.h +++ b/init/bootchart.h @@ -26,6 +26,7 @@ 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 */ diff --git a/init/init.c b/init/init.c index bd1db7a58..99474e6f9 100644 --- a/init/init.c +++ b/init/init.c @@ -65,6 +65,7 @@ static int property_triggers_enabled = 0; #if BOOTCHART static int bootchart_count; +static long long bootchart_time = 0; #endif static char console[32]; @@ -1147,11 +1148,29 @@ int main(int argc, char **argv) #if BOOTCHART if (bootchart_count > 0) { - if (timeout < 0 || timeout > BOOTCHART_POLLING_MS) - timeout = BOOTCHART_POLLING_MS; - if (bootchart_step() < 0 || --bootchart_count == 0) { - bootchart_finish(); - bootchart_count = 0; + long long current_time; + int elapsed_time, remaining_time; + + current_time = bootchart_gettime(); + elapsed_time = current_time - bootchart_time; + + if (elapsed_time >= BOOTCHART_POLLING_MS) { + /* count missed samples */ + while (elapsed_time >= BOOTCHART_POLLING_MS) { + elapsed_time -= BOOTCHART_POLLING_MS; + bootchart_count--; + } + /* count may be negative, take a sample anyway */ + bootchart_time = current_time; + if (bootchart_step() < 0 || bootchart_count <= 0) { + bootchart_finish(); + bootchart_count = 0; + } + } + if (bootchart_count > 0) { + remaining_time = BOOTCHART_POLLING_MS - elapsed_time; + if (timeout < 0 || timeout > remaining_time) + timeout = remaining_time; } } #endif