From f039b754714a422959027cb18bb33760eb8153f0 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 2 May 2007 19:27:12 +0200 Subject: [PATCH] x86: Don't use MWAIT on AMD Family 10 It doesn't put the CPU into deeper sleep states, so it's better to use the standard idle loop to save power. But allow to reenable it anyways for benchmarking. I also removed the obsolete idle=halt on i386 Cc: andreas.herrmann@amd.com Signed-off-by: Andi Kleen --- arch/x86_64/kernel/process.c | 12 +++++++----- arch/x86_64/kernel/setup.c | 6 ++++++ 2 files changed, 13 insertions(+), 5 deletions(-) (limited to 'arch/x86_64') diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index d8d5ccc..4f21765 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -288,16 +288,18 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) static int __init idle_setup (char *str) { - if (!strncmp(str, "poll", 4)) { + if (!strcmp(str, "poll")) { printk("using polling idle threads.\n"); pm_idle = poll_idle; - } + } else if (!strcmp(str, "mwait")) + force_mwait = 1; + else + return -1; boot_option_idle_override = 1; - return 1; + return 0; } - -__setup("idle=", idle_setup); +early_param("idle", idle_setup); /* Prints also some state that isn't saved in the pt_regs */ void __show_regs(struct pt_regs * regs) diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c index 0a1d539..db30b5b 100644 --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -79,6 +79,8 @@ int bootloader_type; unsigned long saved_video_mode; +int force_mwait __cpuinitdata; + /* * Early DMI memory */ @@ -604,6 +606,10 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) /* RDTSC can be speculated around */ clear_bit(X86_FEATURE_SYNC_RDTSC, &c->x86_capability); + + /* Family 10 doesn't support C states in MWAIT so don't use it */ + if (c->x86 == 0x10 && !force_mwait) + clear_bit(X86_FEATURE_MWAIT, &c->x86_capability); } static void __cpuinit detect_ht(struct cpuinfo_x86 *c) -- cgit v1.1