linux-kernel - [tip:x86/platform] x86: numachip: Elide self-IPI ICR polling

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Date:	Tue, 4 Nov 2014 09:21:56 -0800
From:	tip-bot for Daniel J Blueman <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, daniel@...ascale.com,
	linux-kernel@...r.kernel.org, hpa@...or.com, bhelgaas@...gle.com,
	sp@...ascale.com, tglx@...utronix.de
Subject: [tip:x86/platform] x86: numachip: Elide self-IPI ICR polling

Commit-ID:  25e5a76bae106e1673887db09e22b19cb1a86c45
Gitweb:     http://git.kernel.org/tip/25e5a76bae106e1673887db09e22b19cb1a86c45
Author:     Daniel J Blueman <daniel@...ascale.com>
AuthorDate: Tue, 4 Nov 2014 16:29:42 +0800
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 4 Nov 2014 18:17:27 +0100

x86: numachip: Elide self-IPI ICR polling

The default self-IPI path polls the ICR to delay sending the IPI until
there is no IPI in progress. This is redundant on x86-86 APICs, since
IPIs are queued. See the AMD64 Architecture Programmer's Manual, vol 2,
p525.

Signed-off-by: Daniel J Blueman <daniel@...ascale.com>
Cc: Steffen Persvold <sp@...ascale.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Link: http://lkml.kernel.org/r/1415089784-28779-2-git-send-email-daniel@numascale.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/apic/apic_numachip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/apic_numachip.c b/arch/x86/kernel/apic/apic_numachip.c
index 2aaee79..7a31912 100644
--- a/arch/x86/kernel/apic/apic_numachip.c
+++ b/arch/x86/kernel/apic/apic_numachip.c
@@ -145,7 +145,7 @@ static void numachip_send_IPI_all(int vector)
 
 static void numachip_send_IPI_self(int vector)
 {
-	__default_send_IPI_shortcut(APIC_DEST_SELF, vector, APIC_DEST_PHYSICAL);
+	apic_write(APIC_SELF_IPI, vector);
 }
 
 static int __init numachip_probe(void)
--
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