[PATCH] powerpc: Instrument Hypervisor Calls

[Stephen Rothwell]

On Mon, 14 Aug 2006 16:21:44 -0700 Mike Kravetz <kravetz at us.ibm.com> wrote:
>
> diff -Naupr powerpc2/arch/powerpc/platforms/pseries/hvCall.S powerpc2.work/arch/powerpc/platforms/pseries/hvCall.S
> --- powerpc2/arch/powerpc/platforms/pseries/hvCall.S	2006-08-14 18:00:55.000000000 +0000
> +++ powerpc2.work/arch/powerpc/platforms/pseries/hvCall.S	2006-08-14 22:17:04.000000000 +0000
> @@ -10,9 +10,66 @@
>  #include <asm/hvcall.h>
>  #include <asm/processor.h>
>  #include <asm/ppc_asm.h>
> +#include <asm/asm-offsets.h>
>  	
>  #define STK_PARM(i)     (48 + ((i)-3)*8)
>  
> +#ifdef CONFIG_HCALL_STATS
> +/*
> + * precall must preserve all registers.  use unused STK_PARM()
> + * areas to save snapshots and opcode.
> + */
> +#define HCALL_INST_PRECALL					\
> +	std	r3,STK_PARM(r3)(r1);	/* save opcode */	\
> +	mftb	r3;			/* get timebase and */	\
> +	std     r3,STK_PARM(r5)(r1);	/* save for later */	\
> +BEGIN_FTR_SECTION;						\
> +	mfspr	r3,SPRN_PURR;		/* get PURR and */	\
> +END_FTR_SECTION_IFSET(CPU_FTR_PURR);				\
> +	std	r3,STK_PARM(r6)(r1);	/* save for later */	\

So if we have no PURR, we use the TB value (this is fine)

> +	ld	r3,STK_PARM(r3)(r1);	/* opcode back in r3 */
> +	
> +/*
> + * postcall is performed immediately before function return which
> + * allows liberal use of volital registers.
> + */
> +#define HCALL_INST_POSTCALL					\
> +	/* get time and PURR snapshots after hcall */		\
> +	mftb	r7;			/* timebase after */	\
> +BEGIN_FTR_SECTION;						\
> +	mfspr	r8,SPRN_PURR;		/* PURR after */	\
> +END_FTR_SECTION_IFSET(CPU_FTR_PURR);				\
> +								\
> +	/* calculate time and PURR deltas for call */		\
> +	ld	r5,STK_PARM(r5)(r1);	/* timebase before */	\
> +	subf	r5,r5,r7;					\
> +	ld	r6,STK_PARM(r6)(r1);	/* PURR before */	\
> +	subf	r6,r6,r8;					\

But here, if we have no PURR we produce random numbers.  Maybe you should
reuse the TB value so the values reported may make some sense.

-- 
Cheers,
Stephen Rothwell                    sfr at canb.auug.org.au
http://www.canb.auug.org.au/~sfr/
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