Messages in this thread Patch in this message | | | Date | Sun, 5 Oct 2008 17:51:52 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: <PING> Re: [patch x86/core] x86: allow number of additional hotplug CPUs to be set at compile time |
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On Sun, 5 Oct 2008, Ingo Molnar wrote: > > * Thomas Gleixner <tglx@linutronix.de> wrote: > > > On Sun, 5 Oct 2008, Ingo Molnar wrote: > > > * Chuck Ebbert <cebbert@redhat.com> wrote: > > > > > > > Yes, it works and I don't see how it could cause any problems. > > > > > > > > Ingo, can we get this in 2.6.27? You can drop my original patch. > > > > > > > > Tested-by: Chuck Ebbert <cebbert@redhat.com> > > > > > > looks good, applied to tip/x86/core, thanks! > > > > No, this patch is horrible. > > > > The correct check is num_present_cpus(). There is no need to make the > > weird additional_cpus hackery globally available. > > ah, indeed! > > applied to tip/x86/core and i've zapped Andi's patch. > > > Btw, additional_cpus has interesting properties. Providing a negative > > number < -1 on the kernel command line - happened due to a typo - > > explodes in early boot, which is not really surprising, but should be > > sanity checked. > > indeed, and that mess was introduced, interestingly, by this commit, > three years ago, by Andi: > > | From 420f8f68c9c5148dddf946bebdbc7eacde2172cb Mon Sep 17 00:00:00 2001 > | From: Andi Kleen <ak@suse.de> > | Date: Sat, 5 Nov 2005 17:25:54 +0100 > | Subject: [PATCH] [PATCH] x86_64: New heuristics to find out hotpluggable CPUs. > > so to clean up the mess i've removed the additional_cpus= boot parameter > and the Kconfig entry as well - see the patch in x86/core below. > > thanks Thomas for decoding this ... > > and no way can any of this go into v2.6.27: this is fragile code with a > lot of historic baggage and the original error is non-fatal to begin > with. It can easily be backported to .27.1 if testing shows that it has > no other adverse side-effects.
Please lets get rid of all this.
Thanks,
tglx ----------------> From 344707c1f43dd0d080828497aacb60c0cc0a8c13 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@linutronix.de> Date: Sun, 5 Oct 2008 17:27:56 +0200 Subject: [PATCH] x86, smpboot: remove additional_cpus
remove remainder of additional_cpus logic. We now just listen to the disabled_cpus value like we did for years. disabled_cpus is always >= 0 so no need for an extra check.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/smpboot.c | 14 ++------------ 1 files changed, 2 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 3868018..d6a4d95 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1260,8 +1260,6 @@ void __init native_smp_cpus_done(unsigned int max_cpus) check_nmi_watchdog(); } -static int additional_cpus = -1; - /* * cpu_possible_map should be static, it cannot change as cpu's * are onlined, or offlined. The reason is per-cpu data-structures @@ -1281,21 +1279,13 @@ static int additional_cpus = -1; */ __init void prefill_possible_map(void) { - int i; - int possible; + int i, possible; /* no processor from mptable or madt */ if (!num_processors) num_processors = 1; - if (additional_cpus == -1) { - if (disabled_cpus > 0) - additional_cpus = disabled_cpus; - else - additional_cpus = 0; - } - - possible = num_processors + additional_cpus; + possible = num_processors + disabled_cpus; if (possible > NR_CPUS) possible = NR_CPUS;
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