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authorKarel Zak <kzak@redhat.com>2014-07-31 10:15:39 +0200
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2014-08-03 01:12:53 -0400
commitc358d728e7d6bf38a0176a9d5d013c6e972cddbf (patch)
tree8a27c6735605fb635811690b2d474a40a1be983e /man/systemd-bootchart.xml
parent799a8f39d8eb9ea725e85a598c0f5dbd658c8ba7 (diff)
bootchart: don't parse /proc/uptime, use CLOCK_BOOTTIME
* systemd-bootchart always parses /proc/uptime, although the information is unnecessary when --rel specified * use /proc/uptime is overkill, since Linux 2.6.39 we have clock_gettime(CLOCK_BOOTTIME, ...). The backend on kernel side is get_monotonic_boottime() in both cases. * main() uses "if (graph_start <= 0.0)" to detect that /proc is available. This is fragile solution as graph_start is always smaller than zero on all systems after suspend/resume (e.g. laptops), because in this case the system uptime includes suspend time and uptime is always greater number than monotonic time. For example right now difference between uptime and monotonic time is 37 hours on my laptop. Note that main() calls log_uptime() (to parse /proc/uptime) for each sample when it believes that /proc is not available. So on my laptop systemd-boochars spends all live with /proc/uptime parsing + nanosleep(), try strace /usr/lib/systemd/systemd-bootchart to see the never ending loop. This patch uses access("/proc/vmstat", F_OK) to detect procfs.
Diffstat (limited to 'man/systemd-bootchart.xml')
-rw-r--r--man/systemd-bootchart.xml4
1 files changed, 3 insertions, 1 deletions
diff --git a/man/systemd-bootchart.xml b/man/systemd-bootchart.xml
index e19bbc11d4..150ca48f39 100644
--- a/man/systemd-bootchart.xml
+++ b/man/systemd-bootchart.xml
@@ -131,7 +131,9 @@
not graph the time elapsed since boot
and before systemd-bootchart was
started, as it may result in extremely
- large graphs. </para></listitem>
+ large graphs. The time elapsed since boot
+ might also include any time that the system
+ was suspended.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>