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    SubjectRe: [RFC][PATCH 09/11] perf, x86: Implement PERF_SAMPLE_BRANCH_STACK
    On Wed, Mar 03, 2010 at 05:39:45PM +0100, Peter Zijlstra wrote:
    >
    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > ---
    > arch/x86/kernel/cpu/perf_event.c | 14 +++-------
    > arch/x86/kernel/cpu/perf_event_intel.c | 10 ++++++-
    > arch/x86/kernel/cpu/perf_event_intel_ds.c | 16 ++++--------
    > arch/x86/kernel/cpu/perf_event_intel_lbr.c | 20 ++++++++-------
    > include/linux/perf_event.h | 27 +++++++++++++++++---
    > kernel/perf_event.c | 38 ++++++++++++++++++++++-------
    > 6 files changed, 83 insertions(+), 42 deletions(-)
    >
    > Index: linux-2.6/include/linux/perf_event.h
    > ===================================================================
    > --- linux-2.6.orig/include/linux/perf_event.h
    > +++ linux-2.6/include/linux/perf_event.h
    > @@ -126,8 +126,9 @@ enum perf_event_sample_format {
    > PERF_SAMPLE_STREAM_ID = 1U << 9,
    > PERF_SAMPLE_RAW = 1U << 10,
    > PERF_SAMPLE_REGS = 1U << 11,
    > + PERF_SAMPLE_BRANCH_STACK = 1U << 12,
    >
    > - PERF_SAMPLE_MAX = 1U << 12, /* non-ABI */
    > + PERF_SAMPLE_MAX = 1U << 13, /* non-ABI */
    > };
    >
    > /*
    > @@ -395,9 +396,14 @@ enum perf_event_type {
    > * { struct read_format values; } && PERF_SAMPLE_READ
    > * { struct pt_regs regs; } && PERF_SAMPLE_REGS
    > *
    > - * { u64 nr,
    > + * { u64 nr;
    > * u64 ips[nr]; } && PERF_SAMPLE_CALLCHAIN
    > *
    > + * { u64 nr;
    > + * { u64 from, to, flags;
    > + * } lbr[nr]; } && PERF_SAMPLE_BRANCH_STACK
    > + *
    > + *
    > * #
    > * # The RAW record below is opaque data wrt the ABI
    > * #
    > @@ -469,6 +475,17 @@ struct perf_raw_record {
    > void *data;
    > };
    >
    > +struct perf_branch_entry {
    > + __u64 from;
    > + __u64 to;
    > + __u64 flags;
    > +};
    > +
    > +struct perf_branch_stack {
    > + __u64 nr;
    > + struct perf_branch_entry entries[0];
    > +};
    > +
    > struct task_struct;
    >
    > /**
    > @@ -803,13 +820,15 @@ struct perf_sample_data {
    > struct perf_callchain_entry *callchain;
    > struct perf_raw_record *raw;
    > struct pt_regs *regs;
    > + struct perf_branch_stack *branches;
    > };
    >
    > static inline
    > void perf_sample_data_init(struct perf_sample_data *data, u64 addr)
    > {
    > - data->addr = addr;
    > - data->raw = NULL;
    > + data->addr = addr;
    > + data->raw = NULL;
    > + data->branches = NULL;
    > }
    >
    > extern void perf_output_sample(struct perf_output_handle *handle,
    > Index: linux-2.6/kernel/perf_event.c
    > ===================================================================
    > --- linux-2.6.orig/kernel/perf_event.c
    > +++ linux-2.6/kernel/perf_event.c
    > @@ -3189,12 +3189,9 @@ void perf_output_sample(struct perf_outp
    >
    > if (sample_type & PERF_SAMPLE_CALLCHAIN) {
    > if (data->callchain) {
    > - int size = 1;
    > + int size = sizeof(u64);
    >
    > - if (data->callchain)
    > - size += data->callchain->nr;
    > -
    > - size *= sizeof(u64);
    > + size += data->callchain->nr * sizeof(u64);
    >
    > perf_output_copy(handle, data->callchain, size);
    > } else {
    > @@ -3203,6 +3200,20 @@ void perf_output_sample(struct perf_outp
    > }
    > }
    >
    > + if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
    > + if (data->branches) {
    > + int size = sizeof(u64);
    > +
    > + size += data->branches->nr *
    > + sizeof(struct perf_branch_entry);
    > +
    > + perf_output_copy(handle, data->branches, size);
    > + } else {
    > + u64 nr = 0;
    > + perf_output_put(handle, nr);
    > + }
    > + }
    > +
    > if (sample_type & PERF_SAMPLE_RAW) {
    > if (data->raw) {
    > perf_output_put(handle, data->raw->size);
    > @@ -3291,14 +3302,25 @@ void perf_prepare_sample(struct perf_eve
    > }
    >
    > if (sample_type & PERF_SAMPLE_CALLCHAIN) {
    > - int size = 1;
    > + int size = sizeof(u64);
    >
    > data->callchain = perf_callchain(regs);
    >
    > if (data->callchain)
    > - size += data->callchain->nr;
    > + size += data->callchain->nr * sizeof(u64);
    > +
    > + header->size += size;
    > + }
    >
    > - header->size += size * sizeof(u64);
    > + if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
    > + int size = sizeof(u64);
    > +
    > + if (data->branches) {
    > + size += data->branches->nr *
    > + sizeof(struct perf_branch_entry);
    > + }
    > +
    > + header->size += size;
    > }



    That looks good to me, (at least the generic part, as I don't
    know enough the x86 part to tell).



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