linux-kernel - Re: [RFC patch] Use IPI_shortcut for lapic timer broadcast

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Date:	Tue, 30 Jun 2009 15:01:07 +0800
From:	Luming Yu <luming.yu@...il.com>
To:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC patch] Use IPI_shortcut for lapic timer broadcast

Thanks for review. How about the following patch?

/**The patch is enclosed in text attachment**
**Using web client to send the patch**
**below is for review, please apply attached  patch*/


Signed-off-by: Yu Luming <luming.yu@...el.com>

 apic.c         |    5 ++++-
 apic_flat_64.c |    7 ++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)


--- linux-2.6.30-rc6/arch/x86/kernel/apic/apic.c.0	2009-06-29
23:45:05.000000000 -0600
+++ linux-2.6.30-rc6/arch/x86/kernel/apic/apic.c	2009-06-30
00:37:56.000000000 -0600
@@ -419,7 +419,10 @@
 static void lapic_timer_broadcast(const struct cpumask *mask)
 {
 #ifdef CONFIG_SMP
-	apic->send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
+	if (unlikely(cpumask_weight(mask) == num_online_cpus() -1))
+		apic->send_IPI_all(LOCAL_TIMER_VECTOR);
+	else
+		apic->send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
 #endif
 }

--- linux-2.6.30-rc6/arch/x86/kernel/apic/apic_flat_64.c.0	2009-06-29
00:13:26.000000000 -0600
+++ linux-2.6.30-rc6/arch/x86/kernel/apic/apic_flat_64.c	2009-06-29
00:11:23.000000000 -0600
@@ -274,7 +274,12 @@

 static void physflat_send_IPI_all(int vector)
 {
-	physflat_send_IPI_mask(cpu_online_mask, vector);
+	if (vector == NMI_VECTOR) {
+		physflat_send_IPI_mask(cpu_online_mask, vector);
+	} else {
+		__default_send_IPI_shortcut(APIC_DEST_ALLINC,
+					    vector, apic->dest_logical);
+	}
 }

 static unsigned int physflat_cpu_mask_to_apicid(const struct cpumask *cpumask)

Download attachment "1.patch" of type "application/octet-stream" (1084 bytes)