From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Leo Yan <leo.yan@linaro.org>
Cc: alexander.shishkin@linux.intel.com, daniel.lezcano@linaro.org,
sboyd@codeaurora.org, linux-kernel@vger.kernel.org,
acme@kernel.org,
"Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
mingo@redhat.com, john.stultz@linaro.org, tglx@linutronix.de,
jolsa@redhat.com, linux-arm-kernel@lists.infradead.org
Subject: [PATCH 5/5] arm64: perf: Add cap_user_time_short
Date: Tue, 12 May 2020 14:41:03 +0200 [thread overview]
Message-ID: <20200512124451.061059334@infradead.org> (raw)
In-Reply-To: 20200512124058.833263033@infradead.org
This completes the ARM64 cap_user_time support.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/arm64/kernel/perf_event.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1173,6 +1173,7 @@ void arch_perf_update_userpage(struct pe
userpg->cap_user_time = 0;
userpg->cap_user_time_zero = 0;
+ userpg->cap_user_time_short = 0;
do {
rd = sched_clock_read_begin(&seq);
@@ -1183,13 +1184,13 @@ void arch_perf_update_userpage(struct pe
userpg->time_mult = rd->mult;
userpg->time_shift = rd->shift;
userpg->time_zero = rd->epoch_ns;
+ userpg->time_cycle = rd->epoch_cyc;
+ userpg->time_mask = rd->sched_clock_mask;
/*
- * This isn't strictly correct, the ARM64 counter can be
- * 'short' and then we get funnies when it wraps. The correct
- * thing would be to extend the perf ABI with a cycle and mask
- * value, but because wrapping on ARM64 is very rare in
- * practise this 'works'.
+ * Subtract the cycle base, such that software that
+ * doesn't know about cap_user_time_short still 'works'
+ * assuming no wraps.
*/
userpg->time_zero -= (rd->epoch_cyc * rd->mult) >> rd->shift;
@@ -1214,4 +1215,5 @@ void arch_perf_update_userpage(struct pe
*/
userpg->cap_user_time = 1;
userpg->cap_user_time_zero = 1;
+ userpg->cap_user_time_short = 1;
}
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next prev parent reply other threads:[~2020-05-12 12:48 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 12:40 [PATCH 0/5] arm64: perf: Proper cap_user_time* support Peter Zijlstra
2020-05-12 12:40 ` [PATCH 1/5] sched_clock: Expose struct clock_read_data Peter Zijlstra
2020-05-12 12:41 ` [PATCH 2/5] arm64: perf: Implement correct cap_user_time Peter Zijlstra
2020-05-12 14:03 ` Leo Yan
2020-05-12 14:08 ` Peter Zijlstra
2020-05-12 16:05 ` kbuild test robot
2020-05-12 12:41 ` [PATCH 3/5] arm64: perf: Only advertise cap_user_time for arch_timer Peter Zijlstra
2020-05-12 12:41 ` [PATCH 4/5] perf: Add perf_event_mmap_page::cap_user_time_short ABI Peter Zijlstra
2020-05-12 12:41 ` Peter Zijlstra [this message]
2020-05-12 14:11 ` [PATCH 5/5] arm64: perf: Add cap_user_time_short Leo Yan
2020-05-12 16:59 ` kbuild test robot
2020-07-13 6:08 ` [PATCH 0/5] arm64: perf: Proper cap_user_time* support Leo Yan
2020-07-13 10:11 ` Will Deacon
2020-07-13 12:58 ` Leo Yan
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