renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-26 22:24:09 +08:00
Code

Tony Luck found that using the "uptime" trace clock that uses jiffies

Browse Source 
as a counter was converted to nanoseconds (silly), and after 1 hour
 11 minutes and 34 seconds, this monotonic clock would wrap, causing
 havoc with the tracing system and making the clock useless.
 
 He converted that clock to use jiffies_64 and made it into a counter
 instead of nanosecond conversions, and displayed the clock with the
 straight jiffy count, which works much better than it did in the past.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQEcBAABAgAGBQJTzcD+AAoJEKQekfcNnQGuy4UH/2IaAlJov97GTlYcpA6CCOfQ
 S6KYN93V/wbJpoRhcVIyk21ugolPCPCA+W8QEHU/yIzTDuy4VzkiYDfEZSNWL9bF
 36dmYyNQdeFkfhVK0sHW7/OvF/YcbMsd70N1+NuwFu0m/sDFKlPWiGe8F0GDyRQb
 mKDBiAVAAhDtMWycff3iUgA7eJffejf6Hs6Ve9UdxQ4FxvDaS9ISCRzzWkEktlnw
 RPHvZZRCd+TvtugjGdfusHXhnKSdZSkt5c0R0DyyTebW1Wgrq9dJGXxuth+hdoww
 9iQ6o2YhhoxIo49BwxkTJMsLsS4jC+2KmMEepQ3H7BjTUYg5tWMd9kWAAtxKuDI=
 =3sF+
 -----END PGP SIGNATURE-----

Merge tag 'trace-fixes-v3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull trace fix from Steven Rostedt:
 "Tony Luck found that using the "uptime" trace clock that uses jiffies
  as a counter was converted to nanoseconds (silly), and after 1 hour 11
  minutes and 34 seconds, this monotonic clock would wrap, causing havoc
  with the tracing system and making the clock useless.

  He converted that clock to use jiffies_64 and made it into a counter
  instead of nanosecond conversions, and displayed the clock with the
  straight jiffy count, which works much better than it did in the past"

* tag 'trace-fixes-v3.16-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix wraparound problems in "uptime" trace clock
This commit is contained in:
Linus Torvalds 2014-07-21 22:43:15 -07:00
commit 8dcc3be2a4
2 changed files with 6 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/trace/trace.c
View File

@ -823,7 +823,7 @@ static struct {
{ trace_clock_local, "local", 1 },
{ trace_clock_global, "global", 1 },
{ trace_clock_counter, "counter", 0 },
{ trace_clock_jiffies, "uptime", 1 },
{ trace_clock_jiffies, "uptime", 0 },
{ trace_clock, "perf", 1 },
ARCH_TRACE_CLOCKS
};

9
kernel/trace/trace_clock.c
View File

@ -59,13 +59,14 @@ u64 notrace trace_clock(void)
/*
* trace_jiffy_clock(): Simply use jiffies as a clock counter.
* Note that this use of jiffies_64 is not completely safe on
* 32-bit systems. But the window is tiny, and the effect if
* we are affected is that we will have an obviously bogus
* timestamp on a trace event - i.e. not life threatening.
*/
u64 notrace trace_clock_jiffies(void)
{
u64 jiffy = jiffies - INITIAL_JIFFIES;
/* Return nsecs */
return (u64)jiffies_to_usecs(jiffy) * 1000ULL;
return jiffies_64_to_clock_t(jiffies_64 - INITIAL_JIFFIES);
}
/*