Commit graph

4 commits

Author SHA1 Message Date
Anton Blanchard
6f26353ca2 powerpc: tracing: Give hypervisor call tracepoints access to arguments
While most users of the hcall tracepoints will only want the opcode
and return code, some will want all the arguments.  To avoid the
complexity of using varargs we pass a pointer to the register save
area, which contains all the arguments.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2009-10-28 16:13:04 +11:00
Anton Blanchard
c8cd093a6e powerpc: tracing: Add hypervisor call tracepoints
Add hcall_entry and hcall_exit tracepoints.  This replaces the inline
assembly HCALL_STATS code and converts it to use the new tracepoints.

To keep the disabled case as quick as possible, we embed a status word
in the TOC so we can get at it with a single load.  By doing so we
keep the overhead at a minimum.  Time taken for a null hcall:

No tracepoint code:	135.79 cycles
Disabled tracepoints:	137.95 cycles

For reference, before this patch enabling HCALL_STATS resulted in a null
hcall of 201.44 cycles!

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2009-10-28 16:13:04 +11:00
Anton Blanchard
6795b85c6a powerpc: tracing: Add powerpc tracepoints for timer entry and exit
We can monitor the effectiveness of our power management of both the
kernel and hypervisor by probing the timer interrupt. For example, on
this box we see 10.37s timer interrupts on an idle core:

<idle>-0     [010]  3900.671297: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
<idle>-0     [010]  3900.671302: timer_interrupt_exit: pt_regs=c0000000ce1e7b10

<idle>-0     [010]  3911.042963: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
<idle>-0     [010]  3911.042968: timer_interrupt_exit: pt_regs=c0000000ce1e7b10

<idle>-0     [010]  3921.414630: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
<idle>-0     [010]  3921.414635: timer_interrupt_exit: pt_regs=c0000000ce1e7b10

Since we have a 207MHz decrementer it will go negative and fire every 10.37s
even if Linux is completely idle.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2009-10-28 16:13:03 +11:00
Anton Blanchard
1bf4af1650 powerpc: tracing: Add powerpc tracepoints for interrupt entry and exit
This adds powerpc-specific tracepoints for interrupt entry and exit.

While we already have generic irq_handler_entry and irq_handler_exit
tracepoints there are cases on our virtualised powerpc machines where an
interrupt is presented to the OS, but subsequently handled by the hypervisor.
This means no OS interrupt handler is invoked.

Here is an example on a POWER6 machine with the patch below applied:

<idle>-0     [006]  3243.949840744: irq_entry: pt_regs=c0000000ce31fb10
<idle>-0     [006]  3243.949850520: irq_exit: pt_regs=c0000000ce31fb10

<idle>-0     [007]  3243.950218208: irq_entry: pt_regs=c0000000ce323b10
<idle>-0     [007]  3243.950224080: irq_exit: pt_regs=c0000000ce323b10

<idle>-0     [000]  3244.021879320: irq_entry: pt_regs=c000000000a63aa0
<idle>-0     [000]  3244.021883616: irq_handler_entry: irq=87 handler=eth0
<idle>-0     [000]  3244.021887328: irq_handler_exit: irq=87 return=handled
<idle>-0     [000]  3244.021897408: irq_exit: pt_regs=c000000000a63aa0

Here we see two phantom interrupts (no handler was invoked), followed
by a real interrupt for eth0. Without the tracepoints in this patch we
would have missed the phantom interrupts.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2009-10-28 16:13:03 +11:00