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authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2010-07-12 11:49:59 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-10 11:09:21 -0700
commita1e0ea5d94314a56340859097442673890b04ef5 (patch)
treec36591a3eb865beb0bb53630ad4d767b6523ce77 /arch
parentefe5d7f1ad582cafc68624f39ba720e12bcddb20 (diff)
downloadlinux-2.6.34-ux500-a1e0ea5d94314a56340859097442673890b04ef5.tar.gz
xen: drop xen_sched_clock in favour of using plain wallclock time
commit 8a22b9996b001c88f2bfb54c6de6a05fc39e177a upstream. xen_sched_clock only counts unstolen time. In principle this should be useful to the Linux scheduler so that it knows how much time a process actually consumed. But in practice this doesn't work very well as the scheduler expects the sched_clock time to be synchronized between cpus. It also uses sched_clock to measure the time a task spends sleeping, in which case "unstolen time" isn't meaningful. So just use plain xen_clocksource_read to return wallclock nanoseconds for sched_clock. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/xen/enlighten.c2
-rw-r--r--arch/x86/xen/time.c39
2 files changed, 1 insertions, 40 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 65d8d79b46a..27dff06d979 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -927,7 +927,7 @@ static const struct pv_init_ops xen_init_ops __initdata = {
};
static const struct pv_time_ops xen_time_ops __initdata = {
- .sched_clock = xen_sched_clock,
+ .sched_clock = xen_clocksource_read,
};
static const struct pv_cpu_ops xen_cpu_ops __initdata = {
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index b3c6c59ed30..a86df42e46a 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -155,45 +155,6 @@ static void do_stolen_accounting(void)
account_idle_ticks(ticks);
}
-/*
- * Xen sched_clock implementation. Returns the number of unstolen
- * nanoseconds, which is nanoseconds the VCPU spent in RUNNING+BLOCKED
- * states.
- */
-unsigned long long xen_sched_clock(void)
-{
- struct vcpu_runstate_info state;
- cycle_t now;
- u64 ret;
- s64 offset;
-
- /*
- * Ideally sched_clock should be called on a per-cpu basis
- * anyway, so preempt should already be disabled, but that's
- * not current practice at the moment.
- */
- preempt_disable();
-
- now = xen_clocksource_read();
-
- get_runstate_snapshot(&state);
-
- WARN_ON(state.state != RUNSTATE_running);
-
- offset = now - state.state_entry_time;
- if (offset < 0)
- offset = 0;
-
- ret = state.time[RUNSTATE_blocked] +
- state.time[RUNSTATE_running] +
- offset;
-
- preempt_enable();
-
- return ret;
-}
-
-
/* Get the TSC speed from Xen */
unsigned long xen_tsc_khz(void)
{