Messages in this thread Patch in this message | | | Date | Thu, 4 Aug 2005 10:27:12 -0700 | From | Ashok Raj <> | Subject | Re: [patch 5/8] x86_64:Dont do broadcast IPIs when hotplug is enabled in flat mode. |
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On Thu, Aug 04, 2005 at 12:51:07PM +0200, Andi Kleen wrote: > > static void flat_send_IPI_allbutself(int vector) > > { > > +#ifndef CONFIG_HOTPLUG_CPU > > if (((num_online_cpus()) - 1) >= 1) > > __send_IPI_shortcut(APIC_DEST_ALLBUT, vector,APIC_DEST_LOGICAL); > > +#else > > + cpumask_t allbutme = cpu_online_map; > > + int me = get_cpu(); /* Ensure we are not preempted when we clear */ > > + cpu_clear(me, allbutme); > > + flat_send_IPI_mask(allbutme, vector); > > + put_cpu(); > > This still needs the num_online_cpus()s check. > > -Andi
Modified patch attached.
Andrew: the filename in your -mm queue is below, with the attached patch.
x86_64dont-do-broadcast-ipis-when-hotplug-is-enabled-in-flat-mode.patch
-- Cheers, Ashok Raj - Open Source Technology Center
Note: Recent introduction of physflat mode for x86_64 inadvertently deleted the use of non-shortcut version of routines breaking CPU hotplug. The option to select this via cmdline also is deleted with the physflat patch, hence directly placing this code under CONFIG_HOTPLUG_CPU.
We dont want to use broadcast mode IPI's when hotplug is enabled. This causes bad effects in send IPI to a cpu that is offline which can trip when the cpu is in the process of being kicked alive.
Signed-off-by: Ashok Raj <ashok.raj@intel.com> ------------------------------------------------------- arch/x86_64/kernel/genapic_flat.c | 10 ++++++++++ 1 files changed, 10 insertions(+)
Index: linux-2.6.13-rc4-mm1/arch/x86_64/kernel/genapic_flat.c =================================================================== --- linux-2.6.13-rc4-mm1.orig/arch/x86_64/kernel/genapic_flat.c +++ linux-2.6.13-rc4-mm1/arch/x86_64/kernel/genapic_flat.c @@ -78,8 +78,18 @@ static void flat_send_IPI_mask(cpumask_t static void flat_send_IPI_allbutself(int vector) { +#ifndef CONFIG_HOTPLUG_CPU if (((num_online_cpus()) - 1) >= 1) __send_IPI_shortcut(APIC_DEST_ALLBUT, vector,APIC_DEST_LOGICAL); +#else + cpumask_t allbutme = cpu_online_map; + int me = get_cpu(); /* Ensure we are not preempted when we clear */ + cpu_clear(me, allbutme); + + if (!cpus_empty(allbutme)) + flat_send_IPI_mask(allbutme, vector); + put_cpu(); +#endif } static void flat_send_IPI_all(int vector) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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