Le 29/06/2011 16:59, Karel Zak a écrit : > On Fri, May 20, 2011 at 02:06:21PM +0200, corentin.labbe wrote: >> >> This patch add the -H option to dmesg which allow to print human >> readable time instead of the number of seconds since boot. > > Nice idea, but it's not so simple :-( > > The time stamp used for printk() is not based on normal system time > (as you know from gettimeofday()). It uses cpu_clock() (IMHO to > keep printk() robust and without xtime_lock). > > The problem is that the cpu_clock is not updated after system resume, > so if you suspend (e.g. pm-suspend(8)) and resume than the dmesg -H > command prints nonsenses... > > For example (copy & past from /var/log/messages): > > Jun 27 23:39:53 nb kernel: [50065.238635] PM: Syncing filesystems ... done. > Jun 28 20:23:29 nb kernel: [50065.284226] Freezing user space processes ... (elapsed 0.09 seconds) done. > ^^^^^ > The first line is before suspend and second is after resume. The time > stamp [50065.xxxxxx] is still the same although the system was > suspended for almost whole day. > > The same system, the latest kernel message: > > # date > Wed Jun 29 16:29:28 CEST 2011 > > # mount /dev/sdb1 /mnt/test > > # ./sys-utils/dmesg -H | tail -1 > [Tue Jun 28 11:10:41 2011] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: (null) > > > Karel > Perhaps we could keep my patch and add a warning about "problem with suspend/resume" (both at first line when -H is used and in manpages). Like "Warning timestamp could be inaccurate if you have used SUSPEND/RESUME" If you are agree with that I will update my patch accordingly. Bests regards -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
