Hi Peter,
On 07/13/2016 03:42 PM, Peter Zijlstra wrote:
Ok so the nonlinear thing was it doing _two_ copies, one the regular
__output_copy() on raw->data and second the optional fragment thingy
using __output_custom().
Would something like this work instead?
It does the nonlinear thing and the custom copy function thing but
allows more than 2 fragments and allows each fragment to have a custom
copy.
It doesn't look obviously more expensive; it has the one ->copy branch
extra, but then it doesn't recompute the sizes.
Yes, that would work as well on a quick glance with diff just a bit
bigger, but more generic this way. Do you want me to adapt this into
the first patch?
One question below:
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 1fe22032f228..83e2a83e8db3 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -69,9 +69,18 @@ struct perf_callchain_entry_ctx {
bool contexts_maxed;
};
+typedef unsigned long (*perf_copy_f)(void *dst, const void *src, unsigned long
len);
+
+struct perf_raw_frag {
+ struct perf_raw_frag *next;
+ perf_copy_f copy;
+ void *data;
+ u32 size;
+} __packed;
+
struct perf_raw_record {
+ struct perf_raw_frag frag;
u32 size;
- void *data;
};
/*
diff --git a/kernel/events/core.c b/kernel/events/core.c
index fe8d49a56322..f7ad7d65317d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5617,16 +5617,21 @@ void perf_output_sample(struct perf_output_handle
*handle,
}
if (sample_type & PERF_SAMPLE_RAW) {
- if (data->raw) {
- u32 raw_size = data->raw->size;
- u32 real_size = round_up(raw_size + sizeof(u32),
- sizeof(u64)) - sizeof(u32);
- u64 zero = 0;
-
- perf_output_put(handle, real_size);
- __output_copy(handle, data->raw->data, raw_size);
- if (real_size - raw_size)
- __output_copy(handle, &zero, real_size -
raw_size);
+ struct perf_raw_record *raw = data->raw;
+
+ if (raw) {
+ struct perf_raw_frag *frag = &raw->frag;
+
+ perf_output_put(handle, raw->size);
+ do {
+ if (frag->copy) {
+ __output_custom(handle, frag->copy,
+ frag->data, frag->size);
+ } else {
+ __output_copy(handle, frag->data,
frag->size);
+ }
+ frag = frag->next;
+ } while (frag);
We still need the zero padding here from above with the computed
raw->size, right?
} else {
struct {
u32 size;
@@ -5751,14 +5756,22 @@ void perf_prepare_sample(struct perf_event_header
*header,
Thanks,
Daniel
