On Mon, 16 Aug 2004, Andrew Morton wrote:
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> wrote:
Albert Cahalan <albert@xxxxxxxxxxxx> writes:
Even with the 2.6.7 kernel, I'm still getting reports of process
start times wandering. Here is an example:
"About 12 hours since reboot to 2.6.7 there was already a
difference of about 7 seconds between the real start time
and the start time reported by ps. Now, 24 hours since reboot
the difference is 10 seconds."
The calculation used is:
now - uptime + time_from_boot_to_process_start
Start-time and uptime is using different source. Looks like the
jiffies was added bogus lost counts.
quick hack. Does this change the behavior?
Where did this all end up? Complaints about wandering start times are
persistent, and it'd be nice to get some fix in place...
The trouble seems to be due to the patch below, part of a larger cleanup
Quoting from the changelog entry:
"Changes the uptime code to use the posix_clock_monotonic notion of uptime instead of the jiffies. This time will track NTP changes and so should be better than your standard wristwatch (if your using ntp)."
George is absolutely right that it's more precise. However, it's also inconsistent with the process start times which use plain uncorrected jiffies. ps stumbles over this inconsistency.
Simple fix: revert the patch below.
Complicated fix: correct process start times in fork.c (no patch provided, too complicated for me to do).