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From: Daniel J Blueman <daniel@numascale.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Bjorn Helgaas <bhelgaas@google.com>
Cc: Daniel J Blueman <daniel@numascale.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org, Steffen Persvold <sp@numascale.com>
Subject: [PATCH v4 2/4] Numachip: Elide self-IPI ICR polling
Date: Tue,  4 Nov 2014 16:29:42 +0800	[thread overview]
Message-ID: <1415089784-28779-2-git-send-email-daniel@numascale.com> (raw)
In-Reply-To: <1415089784-28779-1-git-send-email-daniel@numascale.com>

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@numascale.com>
---
 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 81d70ba..bd083c0 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)
-- 
1.9.1


  reply	other threads:[~2014-11-04  8:31 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-04  8:29 [PATCH v4 1/4] Numachip: Fix 16-bit APIC ID truncation Daniel J Blueman
2014-11-04  8:29 ` Daniel J Blueman [this message]
2014-11-04  8:29 ` [PATCH v4 3/4] Numachip: APIC driver cleanups Daniel J Blueman
2014-11-04  8:29 ` [PATCH v4 4/4] Use 2GB memory block size on large-memory x86-64 systems Daniel J Blueman
2015-08-21 18:19   ` Luck, Tony
2015-08-21 18:38     ` Yinghai Lu
2015-08-21 20:27       ` Luck, Tony
2015-08-21 20:50         ` Yinghai Lu
2015-08-21 23:54           ` Tony Luck
2015-08-24 17:46             ` Yinghai Lu
2015-08-24 20:41               ` Tony Luck
2015-08-24 21:25                 ` Yinghai Lu
2015-08-24 22:39                   ` Tony Luck
2015-08-24 23:41                     ` Yinghai Lu
2015-08-24 23:59                       ` Yinghai Lu
     [not found]                         ` <CA+8MBbKur4SLh-7EKhU16_ra7gbvnOARg-ZWScJWH9q1hKufZQ@mail.gmail.com>
2015-08-25 19:01                           ` Yinghai Lu
2015-08-25 22:06                             ` Tony Luck
2015-08-26  4:17                         ` Ingo Molnar
2015-08-26  5:42                           ` Yinghai Lu
2015-08-26 20:49                             ` Andrew Morton
2015-08-26 21:15                               ` Yinghai Lu

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