forked from Minki/linux
3bd5a5fc8c
The test uses the newly added cap_usr_time_zero and time_zero of perf_event_mmap_page. TSC from rdtsc is compared with the time from 2 perf events. The test passes if the calculated times are all in the correct order. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lkml.kernel.org/r/1372425741-1676-4-git-send-email-adrian.hunter@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
60 lines
1.2 KiB
C
60 lines
1.2 KiB
C
#include <stdbool.h>
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#include <errno.h>
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#include <linux/perf_event.h>
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#include "../../perf.h"
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#include "../../util/types.h"
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#include "../../util/debug.h"
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#include "tsc.h"
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u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
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{
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u64 time, quot, rem;
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time = ns - tc->time_zero;
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quot = time / tc->time_mult;
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rem = time % tc->time_mult;
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return (quot << tc->time_shift) +
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(rem << tc->time_shift) / tc->time_mult;
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}
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u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
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{
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u64 quot, rem;
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quot = cyc >> tc->time_shift;
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rem = cyc & ((1 << tc->time_shift) - 1);
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return tc->time_zero + quot * tc->time_mult +
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((rem * tc->time_mult) >> tc->time_shift);
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}
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int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
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struct perf_tsc_conversion *tc)
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{
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bool cap_usr_time_zero;
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u32 seq;
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int i = 0;
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while (1) {
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seq = pc->lock;
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rmb();
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tc->time_mult = pc->time_mult;
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tc->time_shift = pc->time_shift;
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tc->time_zero = pc->time_zero;
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cap_usr_time_zero = pc->cap_usr_time_zero;
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rmb();
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if (pc->lock == seq && !(seq & 1))
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break;
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if (++i > 10000) {
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pr_debug("failed to get perf_event_mmap_page lock\n");
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return -EINVAL;
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}
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}
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if (!cap_usr_time_zero)
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return -EOPNOTSUPP;
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return 0;
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}
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