linux-kernel - [17/20] x86, UV: Remove UV delay in starting slave cpus

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Message-Id: <20110826220420.556572913@clark.kroah.org>
Date:	Fri, 26 Aug 2011 15:03:40 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Jack Steiner <steiner@....com>, Ingo Molnar <mingo@...e.hu>
Subject: [17/20] x86, UV: Remove UV delay in starting slave cpus

2.6.33-longterm review patch.  If anyone has any objections, please let us know.

------------------

From: Jack Steiner <steiner@....com>

commit 05e33fc20ea5e493a2a1e7f1d04f43cdf89f83ed upstream.

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>
Link: http://lkml.kernel.org/r/20110805140900.GA6774@sgi.com
Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/kernel/apic/x2apic_uv_x.c |    1 -
 1 file changed, 1 deletion(-)

--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -139,7 +139,6 @@ static int __cpuinit uv_wakeup_secondary
 	    ((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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