[Bug tapsets/3279] New: timer.profile broken on 2.6.18 x86_64

[Bug tapsets/3279] New: timer.profile broken on 2.6.18 x86_64

[hunt at redhat dot com]

To reproduce run systemtap.base/timers.stp

It works on 2.6.17 i686
Does not on 2.6.18 x86_64. 

systemtap starting probe
systemtap ending probe
p = 0
j1 = 3983
j2 = 3509
jmax = 0
ms1 = 8756
ms500 = 70
msmax = 0
unexpected profile count: 0 profiles and 3983 jiffies
systemtap test failure
systemtap test success
systemtap test success
systemtap test success

-- 
           Summary: timer.profile broken on 2.6.18 x86_64
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P1
         Component: tapsets
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: hunt at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=3279

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[Bug tapsets/3279] timer.profile broken on 2.6.18 x86_64

[joshua dot i dot stone at intel dot com]

------- Additional Comments From joshua dot i dot stone at intel dot com  2006-09-28 21:59 -------
Can you give more details about your setup?  It works fine for me on x86_64
2.6.18-1.2689.fc6.

If it's a Xen kernel, then this is a known issue.  On both Xen dom0 and domU,
timer.profile successfully registers its callback but never gets any hits.  We
don't have a bugzilla for it though, so we might want to retask this bug.

-- 


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[Bug tapsets/3279] timer.profile broken on 2.6.18 x86_64

[hunt at redhat dot com]

------- Additional Comments From hunt at redhat dot com  2006-09-29 00:24 -------
(In reply to comment #1)
> If it's a Xen kernel, then this is a known issue.  On both Xen dom0 and domU,

Indeed all the kernels that failed were either dom0 or domU. 

-- 


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[Bug tapsets/3279] timer.profile broken on Xen kernels

[joshua dot i dot stone at intel dot com]

------- Additional Comments From joshua dot i dot stone at intel dot com  2006-09-29 01:04 -------
On Xen kernels, the callback registration for timer.profile is successful (via
register_timer_hook), but it never gets called because profile_tick is never called.

If anyone really needs this, you can approximate the same functionality like so:

  function __set_regs(regs:long) %{
      CONTEXT->regs = (struct pt_regs *)(long)THIS->regs;
  %}
  probe fake.timer.profile = kernel.function("timer_interrupt") {
      __set_regs($regs)
  }

... but this has much higher overhead.  It would be nicer to find a patch for
Xen so that it calls profile_tick properly.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|timer.profile broken on     |timer.profile broken on Xen
                   |2.6.18 x86_64               |kernels


http://sourceware.org/bugzilla/show_bug.cgi?id=3279

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[Bug tapsets/3279] timer.profile broken on Xen kernels

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2006-11-20 21:12 -------
Rik van Riel kindly fixed this kernel bug.
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=214886


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


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