linux-kernel - [tip:x86/urgent] x86, UV: Remove UV delay in starting slave cpus

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Message-ID: <tip-05e33fc20ea5e493a2a1e7f1d04f43cdf89f83ed@git.kernel.org>
Date:	Tue, 9 Aug 2011 14:29:05 GMT
From:	tip-bot for Jack Steiner <steiner@....com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	steiner@....com, stable@...nel.org, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:x86/urgent] x86, UV: Remove UV delay in starting slave cpus

Commit-ID:  05e33fc20ea5e493a2a1e7f1d04f43cdf89f83ed
Gitweb:     http://git.kernel.org/tip/05e33fc20ea5e493a2a1e7f1d04f43cdf89f83ed
Author:     Jack Steiner <steiner@....com>
AuthorDate: Fri, 5 Aug 2011 09:09:00 -0500
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 5 Aug 2011 23:48:34 +0200

x86, UV: Remove UV delay in starting slave cpus

Delete the 10 msec delay between the INIT and SIPI when starting
slave cpus. I can find no requirement for this delay. BIOS also
has similar code sequences without the delay.

Removing the delay reduces boot time by 40 sec. Every bit helps.

Signed-off-by: Jack Steiner <steiner@....com>
Cc: <stable@...nel.org>
Link: http://lkml.kernel.org/r/20110805140900.GA6774@sgi.com
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/kernel/apic/x2apic_uv_x.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index adc66c3..34b1859 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -207,7 +207,6 @@ static int __cpuinit uv_wakeup_secondary(int phys_apicid, unsigned long start_ri
 	    ((start_rip << UVH_IPI_INT_VECTOR_SHFT) >> 12) |
 	    APIC_DM_INIT;
 	uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
-	mdelay(10);
 
 	val = (1UL << UVH_IPI_INT_SEND_SHFT) |
 	    (phys_apicid << UVH_IPI_INT_APIC_ID_SHFT) |
--
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