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Message-ID: <CABPqkBQWvV5w-qyaWmbmqs9+7zaC8kBhmacuAF3FYvw-PCh=9A@mail.gmail.com>
Date: Wed, 24 Oct 2012 10:15:51 +0200
From: Stephane Eranian <eranian@...gle.com>
To: "Yan, Zheng" <zheng.z.yan@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
"ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: Re: [PATCH V2 1/7] perf, x86: Reduce lbr_sel_map size
On Wed, Oct 24, 2012 at 9:49 AM, Yan, Zheng <zheng.z.yan@...el.com> 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@...el.com> wrote:
>>> From: "Yan, Zheng" <zheng.z.yan@...el.com>
>>>
>>> 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@...el.com>
>>> ---
>>> 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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