lkml.org 
[lkml]   [2008]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] shrink printk timestamp field
On Wed, 27 Aug 2008 11:17:59 -0400
Joe Korty <joe.korty@ccur.com> wrote:

> Shrink the printk timestamp field.
>
> Keep the printk timestamp from occupying more of the
> scarce, 80-column console line space than it really needs.
>
> We eliminate the excessive whitespace the field added to
> the line, and reduce timestamp precision from six digits
> (usecs) to three digits (msecs). msecs seems adequate
> for the purpose of tracking boot sequence timing issues.
>
> Signed-off-by: Joe Korty <joe.korty@ccur.com>
>
> Index: 2.6.27-rc4-git4/kernel/printk.c
> ===================================================================
> --- 2.6.27-rc4-git4.orig/kernel/printk.c 2008-08-26 18:23:03.000000000 -0400
> +++ 2.6.27-rc4-git4/kernel/printk.c 2008-08-26 18:23:49.000000000 -0400
> @@ -739,9 +739,9 @@
>
> t = cpu_clock(printk_cpu);
> nanosec_rem = do_div(t, 1000000000);
> - tlen = sprintf(tbuf, "[%5lu.%06lu] ",
> + tlen = sprintf(tbuf, "[%3lu.%03lu] ",
> (unsigned long) t,
> - nanosec_rem / 1000);
> + nanosec_rem / 1000000);
>
> for (tp = tbuf; tp < tbuf + tlen; tp++)
> emit_log_char(*tp);

This is a significant loss in utility.

[ 16.817285] md: Autodetecting RAID arrays.
[ 16.817288] md: Scanned 0 and added 0 devices.
[ 16.817290] md: autorun ...
[ 16.817292] md: ... autorun DONE.

This not-terribly-fast machine can emit printks into the log buffer
within two microseconds. That's a pretty useful ad-hoc timing
factility.

This patch will reduce the precision by a factor of five hundred.


\
 
 \ /
  Last update: 2008-08-30 01:39    [W:0.405 / U:0.300 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site