Bug 214886 - profile_tick not getting called
profile_tick not getting called
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel-xen (Show other bugs)
x86_64 Linux
medium Severity medium
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Assigned To: Rik van Riel
Depends On:
Blocks: 215985
  Show dependency treegraph
Reported: 2006-11-09 16:15 EST by Frank Ch. Eigler
Modified: 2007-11-30 17:07 EST (History)
2 users (show)

See Also:
Fixed In Version: beta2
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2006-12-22 21:24:37 EST
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
fixes profiling by calling profile_tick from timer interrupt (367 bytes, patch)
2006-11-16 15:35 EST, Rik van Riel
no flags Details | Diff

External Trackers
Tracker ID Priority Status Summary Last Updated
Sourceware 3279 None None None Never

  None (edit)
Description Frank Ch. Eigler 2006-11-09 16:15:15 EST
Description of problem:
Tools such as systemtap may hook into the profile_tick notifier
mechanism to get told of low-level timer interrupts.  However,
on xen dom0/domU kernels (both fc6 and rhel5), this notifier
function is reportedly never called.

In contrast, the timer_interrupt dom0/domU function is
getting called as expected.

See systemtap bug #3279 for a little more background.

We're not sure whether this is intentional.  If so, we'd
appreciate guidance as to what dom0/domU hooks we should use
for hooking into the timer interrupt.
Comment 1 Rik van Riel 2006-11-09 16:22:32 EST
Is this on i686 or x86-64, or both?
Comment 2 Frank Ch. Eigler 2006-11-09 16:27:08 EST
According the systemtap developer, broken on x86-64, works on i386.
Comment 3 Rik van Riel 2006-11-09 17:02:54 EST
Interesting, since the timer_interrupt() code is shared between the two.

This narrows it down quite a bit.  Thank you.
Comment 4 Rik van Riel 2006-11-15 17:28:58 EST
From my reading of the code, it really does look like neither x86-64 or i686
would work with the current code.

Frank, could you confirm that the i386 test really was done with a Xen kernel?

I'm asking this because x86-64 and i686 share the same timer_interrupt()
function, which really only calls other functions that are shared between both
architectures. From timer_interrupt() down, there are no differences between
x86-64 and i686...
Comment 5 Frank Ch. Eigler 2006-11-15 17:57:59 EST
Martin, could you check/confirm that i686-xen does work with timer.profile?
Comment 6 Rik van Riel 2006-11-16 15:35:12 EST
Created attachment 141411 [details]
fixes profiling by calling profile_tick from timer interrupt
Comment 7 Martin Hunt 2006-11-20 09:16:05 EST
(In reply to comment #5)
> Martin, could you check/confirm that i686-xen does work with timer.profile?

No. There was probably some confusion in my initial bug report when I said
timer.profile worked on my 686 machine but not on my x86_64 systems. That turned
out to be because only the x86_64 systems were running xen kernels.

I can confirm that Rik's patch fixes things for me on x86_64.
Comment 8 Jay Turner 2006-11-20 14:57:34 EST
QE ack for RHEL5.
Comment 9 Rik van Riel 2006-11-20 15:00:47 EST
Last week my patch was also merged upstream.
Comment 11 Don Zickus 2006-11-29 17:26:51 EST
in 2.6.18-1.2767.el5
Comment 12 RHEL Product and Program Management 2006-12-22 21:24:37 EST
A package has been built which should help the problem described in 
this bug report. This report is therefore being closed with a resolution 
of CURRENTRELEASE. You may reopen this bug report if the solution does 
not work for you.

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