Re: [PATCH V2 1/7] perf, x86: Reduce lbr_sel_map size

From: Yan, Zheng
Date: Wed Oct 24 2012 - 03:48:58 EST

On 10/24/2012 03:28 PM, Stephane Eranian wrote:
> On Wed, Oct 24, 2012 at 7:59 AM, Yan, Zheng <zheng.z.yan@xxxxxxxxx> wrote:
>> From: "Yan, Zheng" <zheng.z.yan@xxxxxxxxx>
>>
>> The index of lbr_sel_map is bit value of perf branch_sample_type.
>> By using bit shift as index, we can reduce lbr_sel_map size.
>>
>> Signed-off-by: Yan, Zheng <zheng.z.yan@xxxxxxxxx>
>> ---
>> arch/x86/kernel/cpu/perf_event.h | 4 +++
>> arch/x86/kernel/cpu/perf_event_intel_lbr.c | 50 ++++++++++++++----------------
>> include/uapi/linux/perf_event.h | 42 +++++++++++++++++--------
>> 3 files changed, 56 insertions(+), 40 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
>> index d3b3bb7..ea6749a 100644
>> --- a/arch/x86/kernel/cpu/perf_event.h
>> +++ b/arch/x86/kernel/cpu/perf_event.h
>> @@ -412,6 +412,10 @@ struct x86_pmu {
>> struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr);
>> };
>>
>> +enum {
>> + PERF_SAMPLE_BRANCH_SELECT_MAP_SIZE = PERF_SAMPLE_BRANCH_MAX_SHIFT,
>> +};
>> +
> What's the point on the extraneous definition?

because later patches will add map PERF_SAMPLE_BRANCH_CALL_STACK, it will make
"PERF_SAMPLE_BRANCH_SELECT_MAP_SIZE != PERF_SAMPLE_BRANCH_MAX_SHIFT"

>
>> #define x86_add_quirk(func_) \
>> do { \
>> static struct x86_pmu_quirk __quirk __initdata = { \
>> diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>> index 31fe046..7d9ae5f 100644
>> --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>> +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
>> @@ -61,10 +61,6 @@ enum {
>> #define LBR_FROM_FLAG_INTX (1ULL << 62)
>> #define LBR_FROM_FLAG_ABORT (1ULL << 61)
>>
>> -#define for_each_branch_sample_type(x) \
>> - for ((x) = PERF_SAMPLE_BRANCH_USER; \
>> - (x) < PERF_SAMPLE_BRANCH_MAX; (x) <<= 1)
>> -
>> /*
>> * x86control flow change classification
>> * x86control flow changes include branches, interrupts, traps, faults
>> @@ -378,14 +374,14 @@ static int intel_pmu_setup_hw_lbr_filter(struct perf_event *event)
>> {
>> struct hw_perf_event_extra *reg;
>> u64 br_type = event->attr.branch_sample_type;
>> - u64 mask = 0, m;
>> - u64 v;
>> + u64 mask = 0, v;
>> + int i;
>>
>> - for_each_branch_sample_type(m) {
>> - if (!(br_type & m))
>> + for (i = 0; i < PERF_SAMPLE_BRANCH_SELECT_MAP_SIZE; i++) {
>
> Why not just define for_each_branch_shift()?

for_each_branch_sample_type has only one user. I think using for(...) here make code more readable.

Regards
Yan, Zheng


>
>> + if (!(br_type & (1U << i)))
>> continue;
>>
>> - v = x86_pmu.lbr_sel_map[m];
>> + v = x86_pmu.lbr_sel_map[i];
>> if (v == LBR_NOT_SUPP)
>> return -EOPNOTSUPP;
>>
>> @@ -631,33 +627,33 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
>> /*
>> * Map interface branch filters onto LBR filters
>> */
>> -static const int nhm_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = {
>> - [PERF_SAMPLE_BRANCH_ANY] = LBR_ANY,
>> - [PERF_SAMPLE_BRANCH_USER] = LBR_USER,
>> - [PERF_SAMPLE_BRANCH_KERNEL] = LBR_KERNEL,
>> - [PERF_SAMPLE_BRANCH_HV] = LBR_IGN,
>> - [PERF_SAMPLE_BRANCH_ANY_RETURN] = LBR_RETURN | LBR_REL_JMP
>> - | LBR_IND_JMP | LBR_FAR,
>> +static const int nhm_lbr_sel_map[PERF_SAMPLE_BRANCH_SELECT_MAP_SIZE] = {
>> + [PERF_SAMPLE_BRANCH_ANY_SHIFT] = LBR_ANY,
>> + [PERF_SAMPLE_BRANCH_USER_SHIFT] = LBR_USER,
>> + [PERF_SAMPLE_BRANCH_KERNEL_SHIFT] = LBR_KERNEL,
>> + [PERF_SAMPLE_BRANCH_HV_SHIFT] = LBR_IGN,
>> + [PERF_SAMPLE_BRANCH_ANY_RETURN_SHIFT] = LBR_RETURN | LBR_REL_JMP
>> + | LBR_IND_JMP | LBR_FAR,
>> /*
>> * NHM/WSM erratum: must include REL_JMP+IND_JMP to get CALL branches
>> */
>> - [PERF_SAMPLE_BRANCH_ANY_CALL] =
>> + [PERF_SAMPLE_BRANCH_ANY_CALL_SHIFT] =
>> LBR_REL_CALL | LBR_IND_CALL | LBR_REL_JMP | LBR_IND_JMP | LBR_FAR,
>> /*
>> * NHM/WSM erratum: must include IND_JMP to capture IND_CALL
>> */
>> - [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL | LBR_IND_JMP,
>> + [PERF_SAMPLE_BRANCH_IND_CALL_SHIFT] = LBR_IND_CALL | LBR_IND_JMP,
>> };
>>
>> -static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = {
>> - [PERF_SAMPLE_BRANCH_ANY] = LBR_ANY,
>> - [PERF_SAMPLE_BRANCH_USER] = LBR_USER,
>> - [PERF_SAMPLE_BRANCH_KERNEL] = LBR_KERNEL,
>> - [PERF_SAMPLE_BRANCH_HV] = LBR_IGN,
>> - [PERF_SAMPLE_BRANCH_ANY_RETURN] = LBR_RETURN | LBR_FAR,
>> - [PERF_SAMPLE_BRANCH_ANY_CALL] = LBR_REL_CALL | LBR_IND_CALL
>> - | LBR_FAR,
>> - [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL,
>> +static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_SELECT_MAP_SIZE] = {
>> + [PERF_SAMPLE_BRANCH_ANY_SHIFT] = LBR_ANY,
>> + [PERF_SAMPLE_BRANCH_USER_SHIFT] = LBR_USER,
>> + [PERF_SAMPLE_BRANCH_KERNEL_SHIFT] = LBR_KERNEL,
>> + [PERF_SAMPLE_BRANCH_HV_SHIFT] = LBR_IGN,
>> + [PERF_SAMPLE_BRANCH_ANY_RETURN_SHIFT] = LBR_RETURN | LBR_FAR,
>> + [PERF_SAMPLE_BRANCH_ANY_CALL_SHIFT] = LBR_REL_CALL | LBR_IND_CALL
>> + | LBR_FAR,
>> + [PERF_SAMPLE_BRANCH_IND_CALL_SHIFT] = LBR_IND_CALL,
>> };
>>
>> /* core */
>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> index d1ffdb6..4a735be 100644
>> --- a/include/uapi/linux/perf_event.h
>> +++ b/include/uapi/linux/perf_event.h
>> @@ -148,20 +148,36 @@ enum perf_event_sample_format {
>> * The branch types can be combined, however BRANCH_ANY covers all types
>> * of branches and therefore it supersedes all the other types.
>> */
>> +enum perf_branch_sample_type_shift {
>> + PERF_SAMPLE_BRANCH_USER_SHIFT = 0, /* user branches */
>> + PERF_SAMPLE_BRANCH_KERNEL_SHIFT = 1, /* kernel branches */
>> + PERF_SAMPLE_BRANCH_HV_SHIFT = 2, /* hypervisor branches */
>> +
>> + PERF_SAMPLE_BRANCH_ANY_SHIFT = 3, /* any branch types */
>> + PERF_SAMPLE_BRANCH_ANY_CALL_SHIFT = 4, /* any call branch */
>> + PERF_SAMPLE_BRANCH_ANY_RETURN_SHIFT = 5, /* any return branch */
>> + PERF_SAMPLE_BRANCH_IND_CALL_SHIFT = 6, /* indirect calls */
>> + PERF_SAMPLE_BRANCH_ABORT_SHIFT = 7, /* transaction aborts */
>> + PERF_SAMPLE_BRANCH_INTX_SHIFT = 8, /* in transaction */
>> + PERF_SAMPLE_BRANCH_NOTX_SHIFT = 9, /* not in transaction */
>> +
>> + PERF_SAMPLE_BRANCH_MAX_SHIFT, /* non-ABI */
>> +};
>> +
>> enum perf_branch_sample_type {
>> - PERF_SAMPLE_BRANCH_USER = 1U << 0, /* user branches */
>> - PERF_SAMPLE_BRANCH_KERNEL = 1U << 1, /* kernel branches */
>> - PERF_SAMPLE_BRANCH_HV = 1U << 2, /* hypervisor branches */
>> -
>> - PERF_SAMPLE_BRANCH_ANY = 1U << 3, /* any branch types */
>> - PERF_SAMPLE_BRANCH_ANY_CALL = 1U << 4, /* any call branch */
>> - PERF_SAMPLE_BRANCH_ANY_RETURN = 1U << 5, /* any return branch */
>> - PERF_SAMPLE_BRANCH_IND_CALL = 1U << 6, /* indirect calls */
>> - PERF_SAMPLE_BRANCH_ABORT = 1U << 7, /* transaction aborts */
>> - PERF_SAMPLE_BRANCH_INTX = 1U << 8, /* in transaction (flag) */
>> - PERF_SAMPLE_BRANCH_NOTX = 1U << 9, /* not in transaction (flag) */
>> -
>> - PERF_SAMPLE_BRANCH_MAX = 1U << 10, /* non-ABI */
>> + PERF_SAMPLE_BRANCH_USER = 1U << PERF_SAMPLE_BRANCH_USER_SHIFT,
>> + PERF_SAMPLE_BRANCH_KERNEL = 1U << PERF_SAMPLE_BRANCH_KERNEL_SHIFT,
>> + PERF_SAMPLE_BRANCH_HV = 1U << PERF_SAMPLE_BRANCH_HV_SHIFT,
>> +
>> + PERF_SAMPLE_BRANCH_ANY = 1U << PERF_SAMPLE_BRANCH_ANY_SHIFT,
>> + PERF_SAMPLE_BRANCH_ANY_CALL = 1U << PERF_SAMPLE_BRANCH_ANY_CALL_SHIFT,
>> + PERF_SAMPLE_BRANCH_ANY_RETURN = 1U << PERF_SAMPLE_BRANCH_ANY_RETURN_SHIFT,
>> + PERF_SAMPLE_BRANCH_IND_CALL = 1U << PERF_SAMPLE_BRANCH_IND_CALL_SHIFT,
>> + PERF_SAMPLE_BRANCH_ABORT = 1U << PERF_SAMPLE_BRANCH_ABORT_SHIFT,
>> + PERF_SAMPLE_BRANCH_INTX = 1U << PERF_SAMPLE_BRANCH_INTX_SHIFT,
>> + PERF_SAMPLE_BRANCH_NOTX = 1U << PERF_SAMPLE_BRANCH_NOTX_SHIFT,
>> +
>> + PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
>> };
>>
>> #define PERF_SAMPLE_BRANCH_PLM_ALL \
>> --
>> 1.7.11.7
>>

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