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| author | Peter Zijlstra <peterz@infradead.org> | 2020-07-16 08:11:28 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-07-20 13:50:47 +0300 |
| commit | 6c0246a4588d418f72acd40a7b7601be403d80a9 (patch) | |
| tree | 31fa7d85271948a94ca2b845485dc5371797bebc /arch/arm64/kernel | |
| parent | 279a811eb520594fac3cd3a541e6c7ea50072ac9 (diff) | |
| download | linux-6c0246a4588d418f72acd40a7b7601be403d80a9.tar.xz | |
perf: Add perf_event_mmap_page::cap_user_time_short ABI
In order to support short clock counters, provide an ABI extension.
As a whole:
u64 time, delta, cyc = read_cycle_counter();
+ if (cap_user_time_short)
+ cyc = time_cycle + ((cyc - time_cycle) & time_mask);
delta = mul_u64_u32_shr(cyc, time_mult, time_shift);
if (cap_user_time_zero)
time = time_zero + delta;
delta += time_offset;
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20200716051130.4359-6-leo.yan@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel')
0 files changed, 0 insertions, 0 deletions