From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk
Cc: Ard Biesheuvel <ardb@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Guenter Roeck <linux@roeck-us.net>,
Peter Zijlstra <peterz@infradead.org>,
Linus Walleij <linus.walleij@linaro.org>,
Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH v4 05/12] ARM: vfp: Record VFP bounces as perf emulation faults
Date: Mon, 20 Mar 2023 14:18:38 +0100 [thread overview]
Message-ID: <20230320131845.3138015-6-ardb@kernel.org> (raw)
In-Reply-To: <20230320131845.3138015-1-ardb@kernel.org>
VFP 'bouncing' occurs when the VFP unit cannot complete the execution of
a VFP instruction, either because it is not implemented at all, or
because the values of the arguments are out of range for the hardware
implementation, and the software needs to step in to complete the
operation.
To give some insight in how much certain programs rely on this bouncing,
record the emulation of a VFP instruction in perf's emulation-faults
counter.
This can be used like so
perf stat -e emulation-faults ./testfloat -all2
and the output will be something like
Performance counter stats for './testfloat -all2':
259,277 emulation-faults:u
6.846432176 seconds time elapsed
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm/vfp/vfpmodule.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 4c7473d2f89a040f..039c8dab990699e2 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -18,6 +18,7 @@
#include <linux/uaccess.h>
#include <linux/user.h>
#include <linux/export.h>
+#include <linux/perf_event.h>
#include <asm/cp15.h>
#include <asm/cputype.h>
@@ -313,6 +314,7 @@ static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
* emulate it.
*/
}
+ perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->ARM_pc);
return exceptions & ~VFP_NAN_FLAG;
}
--
2.39.2
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next prev parent reply other threads:[~2023-03-20 13:20 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 13:18 [PATCH v4 00/12] ARM: vfp: Switch to C API to en/disable softirqs Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 01/12] ARM: vfp: Pass thread_info pointer to vfp_support_entry Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 02/12] ARM: vfp: Pass successful return address via register R3 Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 03/12] ARM: vfp: Fix broken softirq handling with instrumentation enabled Ard Biesheuvel
2023-04-09 14:29 ` Linux regression tracking (Thorsten Leemhuis)
2023-04-10 20:15 ` Guenter Roeck
2023-03-20 13:18 ` [PATCH v4 04/12] ARM: entry: Fix iWMMXT TIF flag handling Ard Biesheuvel
2023-03-21 14:32 ` Linus Walleij
2023-03-21 19:19 ` Nicolas Pitre
2023-03-21 19:32 ` Ard Biesheuvel
2023-03-20 13:18 ` Ard Biesheuvel [this message]
2023-03-21 14:33 ` [PATCH v4 05/12] ARM: vfp: Record VFP bounces as perf emulation faults Linus Walleij
2023-03-20 13:18 ` [PATCH v4 06/12] ARM: vfp: Remove workaround for Feroceon CPUs Ard Biesheuvel
2023-03-21 14:44 ` Linus Walleij
2023-03-21 15:42 ` Ard Biesheuvel
2023-03-21 20:40 ` Linus Walleij
2023-03-22 7:26 ` Arnd Bergmann
2023-03-21 20:00 ` Nicolas Pitre
2023-03-20 13:18 ` [PATCH v4 07/12] ARM: vfp: Reimplement VFP exception entry in C code Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 08/12] ARM: kernel: Get rid of thread_info::used_cp[] array Ard Biesheuvel
2023-03-21 14:58 ` Linus Walleij
2023-03-20 13:18 ` [PATCH v4 09/12] ARM: vfp: Use undef hook for handling VFP exceptions Ard Biesheuvel
2023-03-21 14:59 ` Linus Walleij
2023-03-21 15:41 ` Ard Biesheuvel
2023-03-20 13:18 ` [PATCH v4 10/12] ARM: entry: Disregard Thumb undef exception in coproc dispatch Ard Biesheuvel
2023-03-21 15:05 ` Linus Walleij
2023-03-20 13:18 ` [PATCH v4 11/12] ARM: iwmmxt: Use undef hook to enable coprocessor for task Ard Biesheuvel
2023-03-21 15:06 ` Linus Walleij
2023-03-20 13:18 ` [PATCH v4 12/12] ARM: entry: Make asm coproc dispatch code NWFPE only Ard Biesheuvel
2023-03-21 15:11 ` Linus Walleij
2023-03-23 2:44 ` [PATCH v4 00/12] ARM: vfp: Switch to C API to en/disable softirqs Guenter Roeck
2023-03-23 8:33 ` Ard Biesheuvel
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