diff options
| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2018-01-12 13:45:23 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-01-16 23:47:12 +1100 |
| commit | cd99ddbea250ee79027df6c469f51ad9e5452738 (patch) | |
| tree | bdf7792780f06be984ec2cc200eb725dd10b7a4a /arch/powerpc/perf/8xx-pmu.c | |
| parent | bb9b5a8332533ac7935ca6edfc7ebf15a5366f11 (diff) | |
powerpc/8xx: Only perform perf counting when perf is in use.
In TLB miss handlers, updating the perf counter is only useful
when performing a perf analysis. As it has a noticeable overhead,
let's only do it when needed.
In order to do so, the exit of the miss handlers will be patched
when starting/stopping 'perf': the first register restore
instruction of each exit point will be replaced by a jump to
the counting code.
Once this is done, CONFIG_PPC_8xx_PERF_EVENT becomes useless as
this feature doesn't add any overhead.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/perf/8xx-pmu.c')
| -rw-r--r-- | arch/powerpc/perf/8xx-pmu.c | 52 |
1 files changed, 48 insertions, 4 deletions
diff --git a/arch/powerpc/perf/8xx-pmu.c b/arch/powerpc/perf/8xx-pmu.c index 3c39f05f0af3..6c0020d1c561 100644 --- a/arch/powerpc/perf/8xx-pmu.c +++ b/arch/powerpc/perf/8xx-pmu.c @@ -18,6 +18,7 @@ #include <asm/machdep.h> #include <asm/firmware.h> #include <asm/ptrace.h> +#include <asm/code-patching.h> #define PERF_8xx_ID_CPU_CYCLES 1 #define PERF_8xx_ID_HW_INSTRUCTIONS 2 @@ -30,8 +31,13 @@ extern unsigned long itlb_miss_counter, dtlb_miss_counter; extern atomic_t instruction_counter; +extern unsigned int itlb_miss_perf, dtlb_miss_perf; +extern unsigned int itlb_miss_exit_1, itlb_miss_exit_2; +extern unsigned int dtlb_miss_exit_1, dtlb_miss_exit_2, dtlb_miss_exit_3; static atomic_t insn_ctr_ref; +static atomic_t itlb_miss_ref; +static atomic_t dtlb_miss_ref; static s64 get_insn_ctr(void) { @@ -96,9 +102,24 @@ static int mpc8xx_pmu_add(struct perf_event *event, int flags) val = get_insn_ctr(); break; case PERF_8xx_ID_ITLB_LOAD_MISS: + if (atomic_inc_return(&itlb_miss_ref) == 1) { + unsigned long target = (unsigned long)&itlb_miss_perf; + + patch_branch(&itlb_miss_exit_1, target, 0); +#ifndef CONFIG_PIN_TLB_TEXT + patch_branch(&itlb_miss_exit_2, target, 0); +#endif + } val = itlb_miss_counter; break; case PERF_8xx_ID_DTLB_LOAD_MISS: + if (atomic_inc_return(&dtlb_miss_ref) == 1) { + unsigned long target = (unsigned long)&dtlb_miss_perf; + + patch_branch(&dtlb_miss_exit_1, target, 0); + patch_branch(&dtlb_miss_exit_2, target, 0); + patch_branch(&dtlb_miss_exit_3, target, 0); + } val = dtlb_miss_counter; break; } @@ -143,13 +164,36 @@ static void mpc8xx_pmu_read(struct perf_event *event) static void mpc8xx_pmu_del(struct perf_event *event, int flags) { + /* mfspr r10, SPRN_SPRG_SCRATCH0 */ + unsigned int insn = PPC_INST_MFSPR | __PPC_RS(R10) | + __PPC_SPR(SPRN_SPRG_SCRATCH0); + mpc8xx_pmu_read(event); - if (event_type(event) != PERF_8xx_ID_HW_INSTRUCTIONS) - return; /* If it was the last user, stop counting to avoid useles overhead */ - if (atomic_dec_return(&insn_ctr_ref) == 0) - mtspr(SPRN_ICTRL, 7); + switch (event_type(event)) { + case PERF_8xx_ID_CPU_CYCLES: + break; + case PERF_8xx_ID_HW_INSTRUCTIONS: + if (atomic_dec_return(&insn_ctr_ref) == 0) + mtspr(SPRN_ICTRL, 7); + break; + case PERF_8xx_ID_ITLB_LOAD_MISS: + if (atomic_dec_return(&itlb_miss_ref) == 0) { + patch_instruction(&itlb_miss_exit_1, insn); +#ifndef CONFIG_PIN_TLB_TEXT + patch_instruction(&itlb_miss_exit_2, insn); +#endif + } + break; + case PERF_8xx_ID_DTLB_LOAD_MISS: + if (atomic_dec_return(&dtlb_miss_ref) == 0) { + patch_instruction(&dtlb_miss_exit_1, insn); + patch_instruction(&dtlb_miss_exit_2, insn); + patch_instruction(&dtlb_miss_exit_3, insn); + } + break; + } } static struct pmu mpc8xx_pmu = { |