| From | Ingo Molnar <> | Subject | [PATCH 044/208] x86/fpu: Print out whether we are doing lazy/eager FPU context switches | Date | Tue, 5 May 2015 18:24:24 +0200 |
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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@alien8.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.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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