Messages in this thread | | | Date | Fri, 29 Aug 2008 16:35:40 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] shrink printk timestamp field |
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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.
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