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 v7 1/5] arm64: arm_pmu: remove unnecessary isb instruction Date: Tue, 11 Dec 2018 12:13:36 +0000 [thread overview] Message-ID: <1544530420-1477-2-git-send-email-andrew.murray@arm.com> (raw) In-Reply-To: <1544530420-1477-1-git-send-email-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 8e38d52..de564ae 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -652,7 +652,6 @@ 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) -- 2.7.4
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: Suzuki K Poulose <suzuki.poulose@arm.com>, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Julien Thierry <julien.thierry@arm.com> Subject: [PATCH v7 1/5] arm64: arm_pmu: remove unnecessary isb instruction Date: Tue, 11 Dec 2018 12:13:36 +0000 [thread overview] Message-ID: <1544530420-1477-2-git-send-email-andrew.murray@arm.com> (raw) In-Reply-To: <1544530420-1477-1-git-send-email-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 8e38d52..de564ae 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -652,7 +652,6 @@ 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) -- 2.7.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2018-12-11 12:14 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-12-11 12:13 [PATCH v7 0/5] arm64: Support perf event modifiers :G and :H Andrew Murray 2018-12-11 12:13 ` Andrew Murray 2018-12-11 12:13 ` Andrew Murray [this message] 2018-12-11 12:13 ` [PATCH v7 1/5] arm64: arm_pmu: remove unnecessary isb instruction Andrew Murray 2018-12-11 12:13 ` [PATCH v7 2/5] arm64: KVM: encapsulate kvm_cpu_context in kvm_host_data Andrew Murray 2018-12-11 12:13 ` Andrew Murray 2018-12-11 12:29 ` Christoffer Dall 2018-12-11 12:29 ` Christoffer Dall 2018-12-11 13:11 ` Andrew Murray 2018-12-11 13:11 ` Andrew Murray 2018-12-11 13:40 ` Christoffer Dall 2018-12-11 13:40 ` Christoffer Dall 2018-12-11 14:00 ` Andrew Murray 2018-12-11 14:00 ` Andrew Murray 2018-12-11 12:40 ` Suzuki K Poulose 2018-12-11 12:40 ` Suzuki K Poulose 2018-12-11 13:11 ` Andrew Murray 2018-12-11 13:11 ` Andrew Murray 2018-12-11 12:13 ` [PATCH v7 3/5] arm64: KVM: add accessors to track guest/host only counters Andrew Murray 2018-12-11 12:13 ` Andrew Murray 2018-12-11 12:13 ` [PATCH v7 4/5] arm64: arm_pmu: Add support for exclude_host/exclude_guest attributes Andrew Murray 2018-12-11 12:13 ` Andrew Murray 2018-12-11 12:13 ` [PATCH v7 5/5] arm64: KVM: Enable support for :G/:H perf event modifiers Andrew Murray 2018-12-11 12:13 ` Andrew Murray
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