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authorAshok Raj <ashok.raj@intel.com>2005-06-25 17:55:02 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-25 19:24:31 -0400
commit884d9e40b4089014f40c49e86ac6505842db2b53 (patch)
tree8ff4f3225b46f84a5973074d9c4792b9e744c8e1 /include/asm-x86_64/smp.h
parentcb0cd8d49a9b81aff7a02e2ed826b5cfdfe9a172 (diff)
[PATCH] x86_64: Dont use broadcast shortcut to make it cpu hotplug safe.
Broadcast IPI's provide un-expected behaviour for cpu hotplug. CPU's in offline state also end up receiving the IPI. Once the cpus become online they receive these stale IPI's which are bad and introduce unexpected behaviour. This is easily avoided by not sending a broadcast and addressing just the CPU's in online map. Doing prelim cycle counts it appears there is no big overhead and numbers seem around 0x3000-0x3900 on an average on x86 and x86_64 systems with CPUS running 3G, both for broadcast and mask version of the API's. The shortcuts are useful only for flat mode (where the perf shows no degradation), and in cluster mode, its unicast anyway. Its simpler to just not use broadcast anymore. Signed-off-by: Ashok Raj <ashok.raj@intel.com> Acked-by: Andi Kleen <ak@muc.de> Acked-by: Zwane Mwaikambo <zwane@arm.linux.org.uk> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-x86_64/smp.h')
-rw-r--r--include/asm-x86_64/smp.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-x86_64/smp.h b/include/asm-x86_64/smp.h
index 9c6242fb99db..aeb1b73e21e1 100644
--- a/include/asm-x86_64/smp.h
+++ b/include/asm-x86_64/smp.h
@@ -43,6 +43,8 @@ extern cpumask_t cpu_callout_map;
43extern void smp_alloc_memory(void); 43extern void smp_alloc_memory(void);
44extern volatile unsigned long smp_invalidate_needed; 44extern volatile unsigned long smp_invalidate_needed;
45extern int pic_mode; 45extern int pic_mode;
46extern void lock_ipi_call_lock(void);
47extern void unlock_ipi_call_lock(void);
46extern int smp_num_siblings; 48extern int smp_num_siblings;
47extern void smp_flush_tlb(void); 49extern void smp_flush_tlb(void);
48extern void smp_message_irq(int cpl, void *dev_id, struct pt_regs *regs); 50extern void smp_message_irq(int cpl, void *dev_id, struct pt_regs *regs);