[patch 8/8] x86_64: Choose physflat for AMD systems only when >8 CPUS.

[Ashok Raj]

It is not required to choose the physflat mode when CPU hotplug is enabled 
and CPUs <=8 case. Use of genapic_flat with the mask version is capable of 
doing the same, instead of doing the send_IPI_mask_sequence() where its a 
unicast.

This is another change that Andi introduced with the physflat mode. 

Andi: Do you think this is acceptable?

Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
---------------------------------------------------------------
 arch/x86_64/kernel/genapic.c |    9 +--------
 1 files changed, 1 insertion(+), 8 deletions(-)

Index: linux-2.6.13-rc4-mm1/arch/x86_64/kernel/genapic.c
===================================================================
--- linux-2.6.13-rc4-mm1.orig/arch/x86_64/kernel/genapic.c
+++ linux-2.6.13-rc4-mm1/arch/x86_64/kernel/genapic.c
@@ -69,15 +69,8 @@ void __init clustered_apic_check(void)
 	}
 
 	/* Don't use clustered mode on AMD platforms. */
- 	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ 	if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && (num_cpus > 8)) {
 		genapic = &apic_physflat;
-		/* In the CPU hotplug case we cannot use broadcast mode
-		   because that opens a race when a CPU is removed.
-		   Stay at physflat mode in this case. - AK */
-#ifdef CONFIG_HOTPLUG_CPU
-		if (num_cpus <= 8)
-			genapic = &apic_flat;
-#endif
  		goto print;
  	}
 

--

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