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dmesg: adjust timestamps according to suspended time 

Timestamps in kernel log comes from monotonic clocksource which does not
tick when system suspended. Suspended time easily sums into hours and days
rendering human readable timestamps in dmesg useless.

Adjusting timestamps accouring to current delta between boottime and
monotonic clocksources produces accurate timestamps for messages printed
since last resume. Which are supposed to be most interesting.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
This commit is contained in:
Konstantin Khlebnikov 2020-06-01 22:21:34 +03:00 committed by Karel Zak
parent 4d4f56baad
commit 9bf622dad9
4 changed files with 33 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/monotonic.h
View File

@ -15,6 +15,8 @@
extern int get_boot_time(struct timeval *boot_time);
extern time_t get_suspended_time(void);
extern int gettime_monotonic(struct timeval *tv);
#endif /* UTIL_LINUX_MONOTONIC_H */

12
lib/monotonic.c
View File

@ -48,6 +48,18 @@ int get_boot_time(struct timeval *boot_time)
#endif
}
time_t get_suspended_time(void)
{
#if defined(CLOCK_BOOTTIME) && defined(CLOCK_MONOTONIC)
struct timespec boot, mono;
if (clock_gettime(CLOCK_BOOTTIME, &boot) == 0 &&
clock_gettime(CLOCK_MONOTONIC, &mono) == 0)
return boot.tv_sec - mono.tv_sec;
#endif
return 0;
}
int gettime_monotonic(struct timeval *tv)
{
#ifdef CLOCK_MONOTONIC

2
sys-utils/dmesg.1
View File

@ -161,6 +161,8 @@ source used for the logs is
.B not updated after
system
.BR SUSPEND / RESUME .
Timestamps are adjusted according to current delta between boottime and monotonic
clocks, this works only for messages printed after last resume.
.IP "\fB\-t\fR, \fB\-\-notime\fR"
Do not print kernel's timestamps.
.IP "\fB\-\-time\-format\fR \fIformat\fR"

22
sys-utils/dmesg.c
View File

@ -169,6 +169,7 @@ struct dmesg_control {
struct timeval lasttime; /* last printed timestamp */
struct tm lasttm; /* last localtime */
struct timeval boot_time; /* system boot time */
time_t suspended_time; /* time spent in suspeneded state */
int action; /* SYSLOG_ACTION_* */
int method; /* DMESG_METHOD_* */
@ -824,7 +825,7 @@ static struct tm *record_localtime(struct dmesg_control *ctl,
struct dmesg_record *rec,
struct tm *tm)
{
time_t t = ctl->boot_time.tv_sec + rec->tv.tv_sec;
time_t t = ctl->boot_time.tv_sec + ctl->suspended_time + rec->tv.tv_sec;
return localtime_r(&t, tm);
}
@ -852,7 +853,7 @@ static char *iso_8601_time(struct dmesg_control *ctl, struct dmesg_record *rec,
char *buf, size_t bufsz)
{
struct timeval tv = {
.tv_sec = ctl->boot_time.tv_sec + rec->tv.tv_sec,
.tv_sec = ctl->boot_time.tv_sec + ctl->suspended_time + rec->tv.tv_sec,
.tv_usec = rec->tv.tv_usec
};
@ -1301,8 +1302,16 @@ static inline int dmesg_get_boot_time(struct timeval *tv)
return get_boot_time(tv);
}
static inline time_t dmesg_get_suspended_time(void)
{
if (getenv("DMESG_TEST_BOOTIME"))
return 0;
return get_suspended_time();
}
#else
# define dmesg_get_boot_time get_boot_time
# define dmesg_get_suspended_time get_suspended_time
#endif
int main(int argc, char *argv[])
@ -1499,9 +1508,12 @@ int main(int argc, char *argv[])
if ((is_timefmt(&ctl, RELTIME) ||
is_timefmt(&ctl, CTIME) ||
is_timefmt(&ctl, ISO8601))
&& dmesg_get_boot_time(&ctl.boot_time) != 0)
ctl.time_fmt = DMESG_TIMEFTM_NONE;
is_timefmt(&ctl, ISO8601))) {
if (dmesg_get_boot_time(&ctl.boot_time) != 0)
ctl.time_fmt = DMESG_TIMEFTM_NONE;
else
ctl.suspended_time = dmesg_get_suspended_time();
}
if (delta)
switch (ctl.time_fmt) {