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From: Andrii Nakryiko <andrii@kernel.org>
To: x86@kernel.org, peterz@infradead.org, mingo@redhat.com,
	tglx@linutronix.de
Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	jolsa@kernel.org, song@kernel.org, kernel-team@meta.com,
	Andrii Nakryiko <andrii@kernel.org>,
	Sandipan Das <sandipan.das@amd.com>
Subject: [PATCH v4 1/4] perf/x86/amd: ensure amd_pmu_core_disable_all() is always inlined
Date: Sat, 30 Mar 2024 21:18:27 -0700	[thread overview]
Message-ID: <20240331041830.2806741-2-andrii@kernel.org> (raw)
In-Reply-To: <20240331041830.2806741-1-andrii@kernel.org>

In the following patches we will enable LBR capture on AMD CPUs at
arbitrary point in time, which means that LBR recording won't be frozen
by hardware automatically as part of hardware overflow event. So we need
to take care to minimize amount of branches and function calls/returns
on the path to freezing LBR, minimizing LBR snapshot altering as much as
possible.

amd_pmu_core_disable_all() is one of the functions on this path, and is
already marked as __always_inline. But it calls amd_pmu_set_global_ctl()
which is marked as just inline.  So to guarantee no function call will
be generated thoughout mark amd_pmu_set_global_ctl() as __always_inline
as well.

Reviewed-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 arch/x86/events/amd/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index aec16e581f5b..c5bcbc87d057 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -618,7 +618,7 @@ static void amd_pmu_cpu_dead(int cpu)
 	}
 }
 
-static inline void amd_pmu_set_global_ctl(u64 ctl)
+static __always_inline void amd_pmu_set_global_ctl(u64 ctl)
 {
 	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, ctl);
 }
-- 
2.43.0


  reply	other threads:[~2024-03-31  4:18 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-31  4:18 [PATCH v4 0/4] perf/x86/amd: add LBR capture support outside of hardware events Andrii Nakryiko
2024-03-31  4:18 ` Andrii Nakryiko [this message]
2024-03-31  4:18 ` [PATCH v4 2/4] perf/x86/amd: avoid taking branches before disabling LBR Andrii Nakryiko
2024-03-31  4:18 ` [PATCH v4 3/4] perf/x86/amd: support capturing LBR from software events Andrii Nakryiko
2024-03-31  4:18 ` [PATCH v4 4/4] perf/x86/amd: don't reject non-sampling events with configured LBR Andrii Nakryiko
2024-04-01  9:29 ` [PATCH v4 0/4] perf/x86/amd: add LBR capture support outside of hardware events Ingo Molnar
2024-04-02  2:16   ` Andrii Nakryiko
2024-04-03  8:06     ` Ingo Molnar
2024-04-03 16:08       ` Andrii Nakryiko

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