From: Andrew Murray <andrew.murray@arm.com> To: Christoffer Dall <christoffer.dall@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com> Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [PATCH v13 1/8] arm64: arm_pmu: remove unnecessary isb instruction Date: Tue, 9 Apr 2019 20:22:10 +0100 [thread overview] Message-ID: <20190409192217.23459-2-andrew.murray@arm.com> (raw) In-Reply-To: <20190409192217.23459-1-andrew.murray@arm.com> The armv8pmu_enable_event_counter function issues an isb instruction after enabling a pair of counters - this doesn't provide any value and is inconsistent with the armv8pmu_disable_event_counter. In any case armv8pmu_enable_event_counter is always called with the PMU stopped. Starting the PMU with armv8pmu_start results in an isb instruction being issued prior to writing to PMCR_EL0. Let's remove the unnecessary isb instruction. Signed-off-by: Andrew Murray <andrew.murray@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/kernel/perf_event.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 4addb38bc250..cccf4fc86d67 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -533,7 +533,6 @@ static inline void armv8pmu_enable_event_counter(struct perf_event *event) armv8pmu_enable_counter(idx); if (armv8pmu_event_is_chained(event)) armv8pmu_enable_counter(idx - 1); - isb(); } static inline int armv8pmu_disable_counter(int idx) -- 2.21.0
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Murray <andrew.murray@arm.com> To: Christoffer Dall <christoffer.dall@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com> Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [PATCH v13 1/8] arm64: arm_pmu: remove unnecessary isb instruction Date: Tue, 9 Apr 2019 20:22:10 +0100 [thread overview] Message-ID: <20190409192217.23459-2-andrew.murray@arm.com> (raw) Message-ID: <20190409192210.iJ4R5RVaiXe18h4uHl3DAdU60G2SDKZ0V5zbaZRbcZw@z> (raw) In-Reply-To: <20190409192217.23459-1-andrew.murray@arm.com> The armv8pmu_enable_event_counter function issues an isb instruction after enabling a pair of counters - this doesn't provide any value and is inconsistent with the armv8pmu_disable_event_counter. In any case armv8pmu_enable_event_counter is always called with the PMU stopped. Starting the PMU with armv8pmu_start results in an isb instruction being issued prior to writing to PMCR_EL0. Let's remove the unnecessary isb instruction. Signed-off-by: Andrew Murray <andrew.murray@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> --- arch/arm64/kernel/perf_event.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 4addb38bc250..cccf4fc86d67 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -533,7 +533,6 @@ static inline void armv8pmu_enable_event_counter(struct perf_event *event) armv8pmu_enable_counter(idx); if (armv8pmu_event_is_chained(event)) armv8pmu_enable_counter(idx - 1); - isb(); } static inline int armv8pmu_disable_counter(int idx) -- 2.21.0 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2019-04-09 19:22 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-04-09 19:22 [PATCH v13 0/8] arm64: Support perf event modifiers :G and :H Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-09 19:22 ` Andrew Murray [this message] 2019-04-09 19:22 ` [PATCH v13 1/8] arm64: arm_pmu: remove unnecessary isb instruction Andrew Murray 2019-04-09 19:22 ` [PATCH v13 2/8] arm64: KVM: encapsulate kvm_cpu_context in kvm_host_data Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-09 19:22 ` [PATCH v13 3/8] arm64: KVM: add accessors to track guest/host only counters Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-09 19:22 ` [PATCH v13 4/8] arm64: arm_pmu: Add !VHE support for exclude_host/exclude_guest attributes Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-11 22:28 ` Suzuki K Poulose 2019-04-11 22:28 ` Suzuki K Poulose 2019-04-09 19:22 ` [PATCH v13 5/8] arm64: KVM: Enable !VHE support for :G/:H perf event modifiers Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-15 13:02 ` Suzuki K Poulose 2019-04-15 13:02 ` Suzuki K Poulose 2019-04-09 19:22 ` [PATCH v13 6/8] arm64: KVM: Enable VHE " Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-15 13:43 ` Suzuki K Poulose 2019-04-15 13:43 ` Suzuki K Poulose 2019-04-30 9:54 ` Andrew Murray 2019-04-30 9:54 ` Andrew Murray 2019-04-09 19:22 ` [PATCH v13 7/8] arm64: KVM: avoid isb's by using direct pmxevtyper sysreg Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-15 13:49 ` Suzuki K Poulose 2019-04-15 13:49 ` Suzuki K Poulose 2019-04-29 16:41 ` Andrew Murray 2019-04-29 16:41 ` Andrew Murray 2019-04-09 19:22 ` [PATCH v13 8/8] arm64: docs: document perf event attributes Andrew Murray 2019-04-09 19:22 ` Andrew Murray 2019-04-11 17:18 ` Will Deacon 2019-04-11 17:18 ` Will Deacon 2019-04-15 14:05 ` Suzuki K Poulose 2019-04-15 14:05 ` Suzuki K Poulose
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