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SubjectRe: [RFC][PATCH 09/11] perf_counter: revamp syscall input ABI
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On Thu, 2009-03-19 at 09:15 +1100, Paul Mackerras wrote:
> Peter Zijlstra writes:
>
> > Ah, I thought we should keep a pure 64 bit raw value. You never know
> > what hardware will do.
>
> Oh I see, you use hw_event->raw_event if hw_event->raw is set. I
> missed that before.
>
> Still, you're putting that into hwc->config along with other bits like
> ARCH_PERFMON_EVENTSEL_USR and ARCH_PERFMON_EVENTSEL_OS, so I would
> think we could spare two bits for the type, leaving 62 bits for the
> raw event code. And if that isn't enough, there's the
> hw_event.extra_config_len field, which allows userspace to pass in
> arbitrary amounts of extra PMU configuration data.

Good point, overflow interrupt, and usr/os/hv event filter and enable
bits are usually in the config word.

OK, how about the below? I didn't cut it to 2 bits, as that would
already exhaust the TYPE space -- then again, 60 does feel cramped a
bit..

Index: linux-2.6/include/linux/perf_counter.h
===================================================================
--- linux-2.6.orig/include/linux/perf_counter.h
+++ linux-2.6/include/linux/perf_counter.h
@@ -27,6 +27,12 @@ enum perf_event_types {
PERF_TYPE_HARDWARE = 0,
PERF_TYPE_SOFTWARE = 1,
PERF_TYPE_TRACEPOINT = 2,
+
+ /*
+ * available TYPE space, raw is the max value.
+ */
+
+ PERF_TYPE_RAW = 15,
};

/*
@@ -79,14 +85,8 @@ enum perf_counter_record_type {
* Hardware event to monitor via a performance monitoring counter:
*/
struct perf_counter_hw_event {
- union {
- __u64 raw_event;
- struct {
- __u64 event_id : 32,
- type : 8,
- __reserved_0 : 24;
- };
- };
+ __u64 event_id : 60,
+ type : 4;

__u64 irq_period;
__u64 record_type;
@@ -94,7 +94,6 @@ struct perf_counter_hw_event {

__u64 disabled : 1, /* off by default */
nmi : 1, /* NMI sampling */
- raw : 1, /* raw event type */
inherit : 1, /* children inherit it */
pinned : 1, /* must always be on PMU */
exclusive : 1, /* only group on PMU */
@@ -103,7 +102,7 @@ struct perf_counter_hw_event {
exclude_hv : 1, /* ditto hypervisor */
exclude_idle : 1, /* don't count when idle */

- __reserved_1 : 54;
+ __reserved_1 : 55;

__u32 extra_config_len;
__u32 __reserved_4;



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