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

[Stephane Eranian]

On Wed, Oct 24, 2012 at 9:49 AM, Yan, Zheng <zheng.z.yan@xxxxxxxxx> wrote:
> 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"
>
And you are not going to do:

enum perf_branch_sample_type_shift {
...
PERF_SAMPLE_BRANCH_CALL_STACK_SHIFT = 10
PERF_SAMPLE_BRANCH_MAX_SHIFT
};

PERF_SAMPLE_BRANCH_CALL_STACK = 1 << PERF_SAMPLE_BRANCH_CALL_STACK_SHIFT

Unless you're telling you are not going to add a mapping for
PERF_SAMPLE_CALL_STACK to the
lbr_sel_map[]?


>>
>>>  #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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