• Jack Steiner's avatar
    x86: Reduce clock calibration time during slave cpu startup · b565201c
    Jack Steiner authored
    Reduce the startup time for slave cpus.
    Adds hooks for an arch-specific function for clock calibration.
    These hooks are used on x86.  If a newly started cpu has the
    same phys_proc_id as a core already active, uses the TSC for the
    delay loop and has a CONSTANT_TSC, use the already-calculated
    value of loops_per_jiffy.
    This patch reduces the time required to start slave cpus on a
    4096 cpu system from: 465 sec OLD 62 sec NEW
    This reduces boot time on a 4096p system by almost 7 minutes.
    Signed-off-by: default avatarJack Steiner <steiner@sgi.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: John Stultz <john.stultz@linaro.org>
    [fix CONFIG_SMP=n build]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
calibrate.c 8.31 KB