/var/log/messages, /var/log/syslog, and some other log files use a timestamp which contains an absolute time, like Jan 13 14:13:10.

/var/log/Xorg.0.log and /var/log/dmesg, as well as the output of $ dmesg, use a format that looks like

[50595.991610] malkovich: malkovich malkovich malkovich malkovich

I'm guessing/gathering that the numbers represent seconds and microseconds since startup.

However, my attempt to correlate these two sets of timestamps (using the output from uptime) gave a discrepancy of about 5000 seconds.

This is roughly the amount of time my computer was suspended for.

Is there a convenient way to map the numeric timestamps used by dmesg and Xorg into absolute timestamps?