Commit-ID: 1a744cb356c57303fc97eb15a298032170f841fa Gitweb: http://git.kernel.org/tip/1a744cb356c57303fc97eb15a298032170f841fa Author: Len Brown <[email protected]> AuthorDate: Mon, 11 May 2015 17:27:10 -0400 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 12 May 2015 08:54:33 +0200
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 <[email protected]> Cc: Alan Cox <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Jan H. Schönherr <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/021ce30c88f216ad39686646421194dc25671e55.1431379433.git.len.br...@intel.com Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/smpboot.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 0629a8e..85bd6aa 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
