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Date: Tue, 5 May 2015 18:24:24 +0200
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Andy Lutomirski <luto@...capital.net>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Fenghua Yu <fenghua.yu@...el.com>,
"H. Peter Anvin" <hpa@...or.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Oleg Nesterov <oleg@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 044/208] x86/fpu: Print out whether we are doing lazy/eager FPU context switches
Ever since the kernel started defaulting to eager FPU switches on modern Intel
CPUs it's not been obvious whether a given system is using the lazy or the eager
FPU context switching logic.
So generate a boot message about which mode the FPU code is in:
x86/fpu: Using 'lazy' FPU context switches.
or:
x86/fpu: Using 'eager' FPU context switches.
Reviewed-by: Borislav Petkov <bp@...en8.de>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/kernel/fpu/xsave.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/fpu/xsave.c b/arch/x86/kernel/fpu/xsave.c
index a52205b87acb..61696c5005eb 100644
--- a/arch/x86/kernel/fpu/xsave.c
+++ b/arch/x86/kernel/fpu/xsave.c
@@ -691,6 +691,8 @@ void __init_refok eager_fpu_init(void)
if (eagerfpu == ENABLE)
setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);
+ printk_once(KERN_INFO "x86/fpu: Using '%s' FPU context switches.\n", eagerfpu == ENABLE ? "eager" : "lazy");
+
if (!cpu_has_eager_fpu) {
stts();
return;
--
2.1.0
--
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