6cb9a8350a
The custom_sched_clock hook is broken. The result from sched_clock needs to be in nanoseconds, not in CPU cycles. The TSC is insufficient for this purpose, because TSC is poorly defined in a virtual environment, and mostly represents real world time instead of scheduled process time (which can be interrupted without notice when a virtual machine is descheduled). To make the scheduler consistent, we must expose a different nature of time, that is scheduled time. So deprecate this custom_sched_clock hack and turn it into a paravirt-op, as it should have been all along. This allows the tsc.c code which converts cycles to nanoseconds to be shared by all paravirt-ops backends. It is unfortunate to add a new paravirt-op, but this is a very distinct abstraction which is clearly different for all virtual machine implementations, and it gets rid of an ugly indirect function which I ashamedly admit I hacked in to try to get this to work earlier, and then even got in the wrong units. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
23 lines
481 B
C
23 lines
481 B
C
#ifndef _ASMi386_TIMER_H
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#define _ASMi386_TIMER_H
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#include <linux/init.h>
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#include <linux/pm.h>
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#define TICK_SIZE (tick_nsec / 1000)
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void setup_pit_timer(void);
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unsigned long long native_sched_clock(void);
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/* Modifiers for buggy PIT handling */
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extern int pit_latch_buggy;
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extern int timer_ack;
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extern int no_timer_check;
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extern int no_sync_cmos_clock;
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extern int recalibrate_cpu_khz(void);
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#ifndef CONFIG_PARAVIRT
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#define get_scheduled_cycles(val) rdtscll(val)
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#endif
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#endif
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