x86/smpboot: Remove SIPI delays from cpu_up()

MPS 1.4 example code shows the following required delays during processor
on-lining:

	INIT
	 udelay(10,000)
	SIPI
	 udelay(200)
	SIPI
	 udelay(200) /* Linux actually implements this as udelay(300) */

Linux skips the udelay(10,000) on modern processors.
This patch removes the udelay(200) after each SIPI
on those same processors.

All three legacy delays can be restored by the cmdline
"cpu_init_udelay=10000".

As measured by analyze_suspend.py, this patch speeds
processor resume time on my desktop from 2.4ms to 1.8ms, per AP.

Signed-off-by: Len Brown <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Igor Mammedov <[email protected]>
Cc: Jan H. Schönherr <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Zhu Guihua <[email protected]>
Link: http://lkml.kernel.org/r/a5dfdbc8fbfdd813784da204aad5677fe459ac37.1439739165.git.len.brown@intel.com
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions