git: cputimer: Allow MP synchronized TSC to become cputimer on x86_64

[Sepherosa Ziehau]

commit 8d23b56caf513f5c15f56fb053479cc00fe2eaf4
Author: Sepherosa Ziehau <sephe at dragonflybsd.org>
Date:   Fri Jun 21 09:26:37 2013 +0800

    cputimer: Allow MP synchronized TSC to become cputimer on x86_64
    
    sysclock_t stays as 32bits, as suggested by dillon at .
    
    The TSC cputimer frequency is scaled down TSC frequency (less or equal
    to 128Mhz), which makes 32bits sysclock_t counter hold at least 33
    seconds.
    
    The TSC cputimer is obviously faster than other cputimers, e.g. HPET or
    ACPI timer, so it has the highest priority as of this commit.  It is
    enabled by default, if MP synchronized TSC is detected.  It could be
    disabled by setting tunable hw.tsc_cputimer_enable to 0.

Summary of changes:
 sys/platform/pc64/isa/clock.c | 68 +++++++++++++++++++++++++++++++++++++++++++
 sys/sys/systimer.h            |  2 ++
 2 files changed, 70 insertions(+)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/8d23b56caf513f5c15f56fb053479cc00fe2eaf4


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