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| author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2010-07-12 11:49:59 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-10 11:09:21 -0700 |
| commit | a1e0ea5d94314a56340859097442673890b04ef5 (patch) | |
| tree | c36591a3eb865beb0bb53630ad4d767b6523ce77 /arch | |
| parent | efe5d7f1ad582cafc68624f39ba720e12bcddb20 (diff) | |
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.c | 2 | ||||
| -rw-r--r-- | arch/x86/xen/time.c | 39 |
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) { |