diff options
| author | Len Brown <len.brown@intel.com> | 2015-05-11 17:27:10 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-05-12 08:54:33 +0200 |
| commit | 1a744cb356c57303fc97eb15a298032170f841fa (patch) | |
| tree | 4b53ce69c8ec5a9a7ce3fec39223f213055d1d41 /arch | |
| parent | d68921f9bd148359e6d01c84aaa2e32bfbd82970 (diff) | |
x86/smp/boot: Remove 10ms delay from cpu_up() on modern processors
Modern processor familes do not require the 10ms delay
in cpu_up() to de-assert INIT. This speeds up boot
and resume by 10ms per (application) processor.
Signed-off-by: Len Brown <len.brown@intel.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/021ce30c88f216ad39686646421194dc25671e55.1431379433.git.len.brown@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 0629a8e513af..85bd6aad8c74 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -521,6 +521,7 @@ void __inquire_remote_apic(int apicid) * many cores and don't require that delay. * * Cmdline "init_cpu_udelay=" is available to over-ride this delay. + * Modern processor families are quirked to remove the delay entirely. */ #define UDELAY_10MS_DEFAULT 10000 @@ -534,6 +535,18 @@ static int __init cpu_init_udelay(char *str) } early_param("cpu_init_udelay", cpu_init_udelay); +static void __init smp_quirk_init_udelay(void) +{ + /* if cmdline changed it from default, leave it alone */ + if (init_udelay != UDELAY_10MS_DEFAULT) + return; + + /* if modern processor, use no delay */ + if (((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && (boot_cpu_data.x86 == 6)) || + ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && (boot_cpu_data.x86 >= 0xF))) + init_udelay = 0; +} + /* * Poke the other CPU in the eye via NMI to wake it up. Remember that the normal * INIT, INIT, STARTUP sequence will reset the chip hard for us, and this @@ -1210,6 +1223,8 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) uv_system_init(); set_mtrr_aps_delayed_init(); + + smp_quirk_init_udelay(); } void arch_enable_nonboot_cpus_begin(void) |