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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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2
arch/powerpc/include/asm/hvcall.h
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@@ -274,6 +274,8 @@ struct hcall_stats {
unsigned long num_calls; /* number of calls (on this CPU) */
unsigned long tb_total; /* total wall time (mftb) of calls. */
unsigned long purr_total; /* total cpu time (PURR) of calls. */
unsigned long tb_start;
unsigned long purr_start;
};
#define HCALL_STAT_ARRAY_SIZE ((MAX_HCALL_OPCODE >> 2) + 1)