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powerpc: tracing: Add hypervisor call tracepoints

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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>
This commit is contained in:
Anton Blanchard
2009-10-26 18:50:29 +00:00
committed by Paul Mackerras
parent 6795b85c6a
commit c8cd093a6e
6 changed files with 175 additions and 44 deletions
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45
arch/powerpc/include/asm/trace.h
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@ -76,6 +76,51 @@ TRACE_EVENT(timer_interrupt_exit,
TP_printk("pt_regs=%p", __entry->regs)
);
#ifdef CONFIG_PPC_PSERIES
extern void hcall_tracepoint_regfunc(void);
extern void hcall_tracepoint_unregfunc(void);
TRACE_EVENT_FN(hcall_entry,
TP_PROTO(unsigned long opcode),
TP_ARGS(opcode),
TP_STRUCT__entry(
__field(unsigned long, opcode)
),
TP_fast_assign(
__entry->opcode = opcode;
),
TP_printk("opcode=%lu", __entry->opcode),
hcall_tracepoint_regfunc, hcall_tracepoint_unregfunc
);
TRACE_EVENT_FN(hcall_exit,
TP_PROTO(unsigned long opcode, unsigned long retval),
TP_ARGS(opcode, retval),
TP_STRUCT__entry(
__field(unsigned long, opcode)
__field(unsigned long, retval)
),
TP_fast_assign(
__entry->opcode = opcode;
__entry->retval = retval;
),
TP_printk("opcode=%lu retval=%lu", __entry->opcode, __entry->retval),
hcall_tracepoint_regfunc, hcall_tracepoint_unregfunc
);
#endif
#endif /* _TRACE_POWERPC_H */
#undef TRACE_INCLUDE_PATH