perf_counter: provide misc bits in the event header (6fab0192) · Commits · 戴 / test

Limit the size of each record to 64k (or should we count in multiples of u64 and have a 512K limit?), this gives 16 bits or spare room in the header, which we can use for misc bits, so as to not have to grow the record with u64 every time we have a few bits to report. Signed-off-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> LKML-Reference: <20090408130408.769271806@chello.nl> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

include/linux/perf_counter.h

+5 −1

Original line number	Diff line number	Diff line
		@@ -201,9 +201,13 @@ struct perf_counter_mmap_page {
		__u32 data_head; /* head in the data section */
		};

		#define PERF_EVENT_MISC_KERNEL (1 << 0)
		#define PERF_EVENT_MISC_USER (1 << 1)

		struct perf_event_header {
		__u32 type;
		__u32 size;
		__u16 misc;
		__u16 size;
		};

		enum perf_event_type {

kernel/perf_counter.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1831,6 +1831,9 @@ static void perf_counter_output(struct perf_counter *counter,
		header.type = PERF_EVENT_COUNTER_OVERFLOW;
		header.size = sizeof(header);

		header.misc = user_mode(regs) ?
		PERF_EVENT_MISC_USER : PERF_EVENT_MISC_KERNEL;

		if (record_type & PERF_RECORD_IP) {
		ip = instruction_pointer(regs);
		header.type \|= __PERF_EVENT_IP;

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