* [Bug runtime/9822] New: reduce timer load
@ 2009-02-04 22:43 fche at redhat dot com
2009-02-04 23:14 ` [Bug runtime/9822] " wcohen at redhat dot com
` (5 more replies)
0 siblings, 6 replies; 8+ messages in thread
From: fche at redhat dot com @ 2009-02-04 22:43 UTC (permalink / raw)
To: systemtap
Two sources of timer/wakeup traffic from the systemtap runtime
should be reduced:
- the runtime/time.c timekeeping widgetry that uses jiffies to keep the per-cpu
khz estimates updated
- the runtime/transport/utt.c stuff that flushes buffers to userspace
--
Summary: reduce timer load
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: runtime
AssignedTo: systemtap at sources dot redhat dot com
ReportedBy: fche at redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=9822
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* [Bug runtime/9822] reduce timer load
2009-02-04 22:43 [Bug runtime/9822] New: reduce timer load fche at redhat dot com
@ 2009-02-04 23:14 ` wcohen at redhat dot com
2009-02-05 0:49 ` mhiramat at redhat dot com
` (4 subsequent siblings)
5 siblings, 0 replies; 8+ messages in thread
From: wcohen at redhat dot com @ 2009-02-04 23:14 UTC (permalink / raw)
To: systemtap
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |wcohen at redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=9822
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* [Bug runtime/9822] reduce timer load
2009-02-04 22:43 [Bug runtime/9822] New: reduce timer load fche at redhat dot com
2009-02-04 23:14 ` [Bug runtime/9822] " wcohen at redhat dot com
@ 2009-02-05 0:49 ` mhiramat at redhat dot com
2009-02-20 11:25 ` ananth at in dot ibm dot com
` (3 subsequent siblings)
5 siblings, 0 replies; 8+ messages in thread
From: mhiramat at redhat dot com @ 2009-02-05 0:49 UTC (permalink / raw)
To: systemtap
------- Additional Comments From mhiramat at redhat dot com 2009-02-04 23:41 -------
(In reply to comment #0)
> - the runtime/time.c timekeeping widgetry that uses jiffies to keep the per-cpu
> khz estimates updated
This ensures the accuracy of the self-own version of gettimeofday_*.
- if the script doesn't use gettimeofday_*, just disable timer. And if the
script use gettimeofday_s, increase the timer interval.
or
- after cpu-khz estimating period, don't use timer(or increase interval to 1sec)
until cpu-freq is changed.
or
- improve upstream kernel not to use locks.
> - the runtime/transport/utt.c stuff that flushes buffers to userspace
This is for avoiding deadlock of global timer lock. I think one possible
solution is using tracepoint in scheduler to wakeup waiting reader thread as
ftrace do.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=9822
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* [Bug runtime/9822] reduce timer load
2009-02-04 22:43 [Bug runtime/9822] New: reduce timer load fche at redhat dot com
2009-02-04 23:14 ` [Bug runtime/9822] " wcohen at redhat dot com
2009-02-05 0:49 ` mhiramat at redhat dot com
@ 2009-02-20 11:25 ` ananth at in dot ibm dot com
2009-02-20 13:16 ` fche at redhat dot com
` (2 subsequent siblings)
5 siblings, 0 replies; 8+ messages in thread
From: ananth at in dot ibm dot com @ 2009-02-20 11:25 UTC (permalink / raw)
To: systemtap
------- Additional Comments From ananth at in dot ibm dot com 2009-02-20 06:49 -------
Any updates on this? From what I hear, this is limiting SystemTap's usefulness
in work that involves power management.
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What |Removed |Added
----------------------------------------------------------------------------
CC| |ananth at in dot ibm dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=9822
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* [Bug runtime/9822] reduce timer load
2009-02-04 22:43 [Bug runtime/9822] New: reduce timer load fche at redhat dot com
` (2 preceding siblings ...)
2009-02-20 11:25 ` ananth at in dot ibm dot com
@ 2009-02-20 13:16 ` fche at redhat dot com
2009-02-24 1:30 ` mhiramat at redhat dot com
2009-02-24 2:45 ` jistone at redhat dot com
5 siblings, 0 replies; 8+ messages in thread
From: fche at redhat dot com @ 2009-02-20 13:16 UTC (permalink / raw)
To: systemtap
------- Additional Comments From fche at redhat dot com 2009-02-20 12:39 -------
> Any updates on this?
No one has yet grabbed this bug.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=9822
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* [Bug runtime/9822] reduce timer load
2009-02-04 22:43 [Bug runtime/9822] New: reduce timer load fche at redhat dot com
` (3 preceding siblings ...)
2009-02-20 13:16 ` fche at redhat dot com
@ 2009-02-24 1:30 ` mhiramat at redhat dot com
2009-02-24 2:45 ` jistone at redhat dot com
5 siblings, 0 replies; 8+ messages in thread
From: mhiramat at redhat dot com @ 2009-02-24 1:30 UTC (permalink / raw)
To: systemtap
------- Additional Comments From mhiramat at redhat dot com 2009-02-23 20:52 -------
(In reply to comment #1)
> > - the runtime/transport/utt.c stuff that flushes buffers to userspace
>
> This is for avoiding deadlock of global timer lock. I think one possible
> solution is using tracepoint in scheduler to wakeup waiting reader thread as
> ftrace do.
Hmm, as far as I can see, current ftrace has deadlock problem...
--
http://sourceware.org/bugzilla/show_bug.cgi?id=9822
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* [Bug runtime/9822] reduce timer load
2009-02-04 22:43 [Bug runtime/9822] New: reduce timer load fche at redhat dot com
` (4 preceding siblings ...)
2009-02-24 1:30 ` mhiramat at redhat dot com
@ 2009-02-24 2:45 ` jistone at redhat dot com
5 siblings, 0 replies; 8+ messages in thread
From: jistone at redhat dot com @ 2009-02-24 2:45 UTC (permalink / raw)
To: systemtap
------- Additional Comments From jistone at redhat dot com 2009-02-23 23:29 -------
(In reply to comment #1)
> > - the runtime/time.c timekeeping widgetry that uses jiffies to keep the
> > per-cpu khz estimates updated
>
> This ensures the accuracy of the self-own version of gettimeofday_*.
> - if the script doesn't use gettimeofday_*, just disable timer.
I just committed a change to this effect, so we should be in a lot better shape.
For an idle script that doesn't call gettimeofday, powertop tells me that I
went from 88.9% C3 residency to 97.1% (vs. 98.3% without stap).
Many of the other suggestions here are still valid, but I think this was the
biggest step.
--
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* [Bug runtime/9822] reduce timer load
[not found] <bug-9822-6586@http.sourceware.org/bugzilla/>
@ 2013-10-12 20:22 ` fche at redhat dot com
0 siblings, 0 replies; 8+ messages in thread
From: fche at redhat dot com @ 2013-10-12 20:22 UTC (permalink / raw)
To: systemtap
https://sourceware.org/bugzilla/show_bug.cgi?id=9822
Frank Ch. Eigler <fche at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #8 from Frank Ch. Eigler <fche at redhat dot com> ---
commig 72f51bc finally adds a STP_TIME_SYNC_INTERVAL
parameter, with much larger defaults.
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Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2009-02-04 22:43 [Bug runtime/9822] New: reduce timer load fche at redhat dot com
2009-02-04 23:14 ` [Bug runtime/9822] " wcohen at redhat dot com
2009-02-05 0:49 ` mhiramat at redhat dot com
2009-02-20 11:25 ` ananth at in dot ibm dot com
2009-02-20 13:16 ` fche at redhat dot com
2009-02-24 1:30 ` mhiramat at redhat dot com
2009-02-24 2:45 ` jistone at redhat dot com
[not found] <bug-9822-6586@http.sourceware.org/bugzilla/>
2013-10-12 20:22 ` fche at redhat dot com
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