[PATCH v6 1/7] perf/core: Define the common branch type classification
Peter Zijlstra
peterz at infradead.org
Fri Jul 7 18:42:01 AEST 2017
PPC folks, maddy, does this work for you guys?
On Thu, Apr 20, 2017 at 08:07:49PM +0800, Jin Yao wrote:
> It is often useful to know the branch types while analyzing branch
> data. For example, a call is very different from a conditional branch.
>
> Currently we have to look it up in binary while the binary may later
> not be available and even the binary is available but user has to take
> some time. It is very useful for user to check it directly in perf
> report.
>
> Perf already has support for disassembling the branch instruction
> to get the x86 branch type.
>
> To keep consistent on kernel and userspace and make the classification
> more common, the patch adds the common branch type classification
> in perf_event.h.
>
> PERF_BR_NONE : unknown
> PERF_BR_JCC : conditional jump
> PERF_BR_JMP : jump
> PERF_BR_IND_JMP : indirect jump
> PERF_BR_CALL : call
> PERF_BR_IND_CALL : indirect call
> PERF_BR_RET : return
> PERF_BR_SYSCALL : syscall
> PERF_BR_SYSRET : syscall return
> PERF_BR_IRQ : hw interrupt/trap/fault
> PERF_BR_INT : sw interrupt
> PERF_BR_IRET : return from interrupt
> PERF_BR_FAR_BRANCH: not generic far branch type
>
> The patch also adds a new field type (4 bits) in perf_branch_entry
> to record the branch type.
>
> Since the disassembling of branch instruction needs some overhead,
> a new PERF_SAMPLE_BRANCH_TYPE_SAVE is introduced to indicate if it
> needs to disassemble the branch instruction and record the branch
> type.
>
> Change log
> ----------
>
> v6: Not changed.
>
> v5: Not changed. The v5 patch series just change the userspace.
>
> v4: Comparing to previous version, the major changes are:
>
> 1. Remove the PERF_BR_JCC_FWD/PERF_BR_JCC_BWD, they will be
> computed later in userspace.
>
> 2. Remove the "cross" field in perf_branch_entry. The cross page
> computing will be done later in userspace.
>
> Signed-off-by: Jin Yao <yao.jin at linux.intel.com>
> ---
> include/uapi/linux/perf_event.h | 29 ++++++++++++++++++++++++++++-
> tools/include/uapi/linux/perf_event.h | 29 ++++++++++++++++++++++++++++-
> 2 files changed, 56 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index d09a9cd..69af012 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -174,6 +174,8 @@ enum perf_branch_sample_type_shift {
> PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT = 14, /* no flags */
> PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT = 15, /* no cycles */
>
> + PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT = 16, /* save branch type */
> +
> PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
> };
>
> @@ -198,9 +200,32 @@ enum perf_branch_sample_type {
> PERF_SAMPLE_BRANCH_NO_FLAGS = 1U << PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT,
> PERF_SAMPLE_BRANCH_NO_CYCLES = 1U << PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT,
>
> + PERF_SAMPLE_BRANCH_TYPE_SAVE =
> + 1U << PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT,
> +
> PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
> };
>
> +/*
> + * Common flow change classification
> + */
> +enum {
> + PERF_BR_NONE = 0, /* unknown */
> + PERF_BR_JCC = 1, /* conditional jump */
> + PERF_BR_JMP = 2, /* jump */
> + PERF_BR_IND_JMP = 3, /* indirect jump */
> + PERF_BR_CALL = 4, /* call */
> + PERF_BR_IND_CALL = 5, /* indirect call */
> + PERF_BR_RET = 6, /* return */
> + PERF_BR_SYSCALL = 7, /* syscall */
> + PERF_BR_SYSRET = 8, /* syscall return */
> + PERF_BR_IRQ = 9, /* hw interrupt/trap/fault */
> + PERF_BR_INT = 10, /* sw interrupt */
> + PERF_BR_IRET = 11, /* return from interrupt */
> + PERF_BR_FAR_BRANCH = 12, /* not generic far branch type */
> + PERF_BR_MAX,
> +};
> +
> #define PERF_SAMPLE_BRANCH_PLM_ALL \
> (PERF_SAMPLE_BRANCH_USER|\
> PERF_SAMPLE_BRANCH_KERNEL|\
> @@ -999,6 +1024,7 @@ union perf_mem_data_src {
> * in_tx: running in a hardware transaction
> * abort: aborting a hardware transaction
> * cycles: cycles from last branch (or 0 if not supported)
> + * type: branch type
> */
> struct perf_branch_entry {
> __u64 from;
> @@ -1008,7 +1034,8 @@ struct perf_branch_entry {
> in_tx:1, /* in transaction */
> abort:1, /* transaction abort */
> cycles:16, /* cycle count to last branch */
> - reserved:44;
> + type:4, /* branch type */
> + reserved:40;
> };
>
> #endif /* _UAPI_LINUX_PERF_EVENT_H */
> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
> index d09a9cd..69af012 100644
> --- a/tools/include/uapi/linux/perf_event.h
> +++ b/tools/include/uapi/linux/perf_event.h
> @@ -174,6 +174,8 @@ enum perf_branch_sample_type_shift {
> PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT = 14, /* no flags */
> PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT = 15, /* no cycles */
>
> + PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT = 16, /* save branch type */
> +
> PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
> };
>
> @@ -198,9 +200,32 @@ enum perf_branch_sample_type {
> PERF_SAMPLE_BRANCH_NO_FLAGS = 1U << PERF_SAMPLE_BRANCH_NO_FLAGS_SHIFT,
> PERF_SAMPLE_BRANCH_NO_CYCLES = 1U << PERF_SAMPLE_BRANCH_NO_CYCLES_SHIFT,
>
> + PERF_SAMPLE_BRANCH_TYPE_SAVE =
> + 1U << PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT,
> +
> PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
> };
>
> +/*
> + * Common flow change classification
> + */
> +enum {
> + PERF_BR_NONE = 0, /* unknown */
> + PERF_BR_JCC = 1, /* conditional jump */
> + PERF_BR_JMP = 2, /* jump */
> + PERF_BR_IND_JMP = 3, /* indirect jump */
> + PERF_BR_CALL = 4, /* call */
> + PERF_BR_IND_CALL = 5, /* indirect call */
> + PERF_BR_RET = 6, /* return */
> + PERF_BR_SYSCALL = 7, /* syscall */
> + PERF_BR_SYSRET = 8, /* syscall return */
> + PERF_BR_IRQ = 9, /* hw interrupt/trap/fault */
> + PERF_BR_INT = 10, /* sw interrupt */
> + PERF_BR_IRET = 11, /* return from interrupt */
> + PERF_BR_FAR_BRANCH = 12, /* not generic far branch type */
> + PERF_BR_MAX,
> +};
> +
> #define PERF_SAMPLE_BRANCH_PLM_ALL \
> (PERF_SAMPLE_BRANCH_USER|\
> PERF_SAMPLE_BRANCH_KERNEL|\
> @@ -999,6 +1024,7 @@ union perf_mem_data_src {
> * in_tx: running in a hardware transaction
> * abort: aborting a hardware transaction
> * cycles: cycles from last branch (or 0 if not supported)
> + * type: branch type
> */
> struct perf_branch_entry {
> __u64 from;
> @@ -1008,7 +1034,8 @@ struct perf_branch_entry {
> in_tx:1, /* in transaction */
> abort:1, /* transaction abort */
> cycles:16, /* cycle count to last branch */
> - reserved:44;
> + type:4, /* branch type */
> + reserved:40;
> };
>
> #endif /* _UAPI_LINUX_PERF_EVENT_H */
> --
> 2.7.4
>
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