Lv, Hui
2011-Apr-20 08:17 UTC
[Xen-devel] Does xen 4.1.0 support high resolution clocksource for tickless kernel (HVM guest)?
Hi guys Does anyone know how to assign a high resolution clocksource to a HVM guest? In my environment, the RHEL6''s HVM guest kernel is 2.6.32.12 based, which is the tickles kernel. I got the timer information of this HVM guest as following: When I "cat /sys/devices/system/clocksource/clocksource0/available_clocksource", it shows three available clocksources: tsc hpet acpi_pm jiffies and the current time source is, "cat /sys/devices/system/clocksource/clocksource0/current_clocksource" tsc However, when I "cat /proc/timer_list": It shows the resolution as ".resolution: 999848 nsecs", which is low resolution. The event_handler is tick_handle_periodic, which is not tickles one-shot mode. In the periodic mode, it triggers 1000 timer interrupts per second, that will bring in some overhead. The nohz_mode is 0, which means "dynamic ticks" was not enabled. So, my question is that, can I assign a high resolution timer to HVM guest? How can the tickles kernel use non-periodic event handler, like "hrtimer_interrupt"? Detail Information from "cat /proc/timer_list" ________________________________________________________________________________________________________________ Timer List Version: v0.5 HRTIMER_MAX_CLOCK_BASES: 2 now at 15852107490831 nsecs cpu: 0 clock 0: .base: ffff880001e11e88 .index: 0 .resolution: 999848 nsecs .get_time: ktime_get_real .offset: 0 nsecs active timers: #0: <ffff88007bc69d18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, java/1147 # expires at 1304150196954680000-1304150196954730000 nsecs [in 1304134344847189169 to 1304134344847239169 nsecs] #1: <ffff88003766dd18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, java/1161 # expires at 1304150263786719000-1304150263786769000 nsecs [in 1304134411679228169 to 1304134411679278169 nsecs] #2: <ffff88007bfafd18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, java/1160 # expires at 1304150263789719000-1304150263789769000 nsecs [in 1304134411682228169 to 1304134411682278169 nsecs] clock 1: .base: ffff880001e11ec8 .index: 1 .resolution: 999848 nsecs .get_time: ktime_get .offset: 0 nsecs active timers: #0: init_task_group, sched_rt_period_timer, S:01, __enqueue_rt_entity, swapper/1 # expires at 15853000000000-15853000000000 nsecs [in 892509169 to 892509169 nsecs] #1: <ffff88007b7bba68>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, abrtd/1115 # expires at 15857231144038-15857331144038 nsecs [in 5123653207 to 5223653207 nsecs] #2: <ffff8800377a3a68>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, avahi-daemon/998 # expires at 17409770144038-17409870144038 nsecs [in 1557662653207 to 1557762653207 nsecs] #3: <ffff88007a0ad918>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, rsyslogd/897 # expires at 86414794559634-86414894559634 nsecs [in 70562687068803 to 70562787068803 nsecs] .expires_next : 9223372036854775807 nsecs .hres_active : 0 .nr_events : 0 .nr_retries : 0 .nr_hangs : 0 .max_hang_time : 0 nsecs .nohz_mode : 0 .idle_tick : 0 nsecs .tick_stopped : 0 .idle_jiffies : 0 .idle_calls : 0 .idle_sleeps : 0 .idle_entrytime : 15852106973443 nsecs .idle_waketime : 0 nsecs .idle_exittime : 0 nsecs .idle_sleeptime : 2015652774896 nsecs .iowait_sleeptime: 988743384 nsecs .last_jiffies : 0 .next_jiffies : 0 .idle_expires : 0 nsecs jiffies: 4310519631 cpu: 1 clock 0: .base: ffff880001e31e88 .index: 0 .resolution: 999848 nsecs .get_time: ktime_get_real .offset: 0 nsecs active timers: #0: <ffff88007bcafd18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, java/1154 # expires at 1304150196915577000-1304150196915627000 nsecs [in 1304134344808086169 to 1304134344808136169 nsecs] #1: <ffff88007a07fd18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, automount/1090 # expires at 1304150197124171000-1304150197124221000 nsecs [in 1304134345016680169 to 1304134345016730169 nsecs] #2: <ffff880037493d18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, automount/1089 # expires at 1304150238123676000-1304150238123726000 nsecs [in 1304134386016185169 to 1304134386016235169 nsecs] #3: <ffff88007baf9d18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, rs:main Q:Reg/1854 # expires at 1304150245664082612-1304150245664132612 nsecs [in 1304134393556591781 to 1304134393556641781 nsecs] #4: <ffff88007b947d18>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, java/1158 # expires at 1304152363782719000-1304152363782769000 nsecs [in 1304136511675228169 to 1304136511675278169 nsecs] clock 1: .base: ffff880001e31ec8 .index: 1 .resolution: 999848 nsecs .get_time: ktime_get .offset: 0 nsecs active timers: #0: <ffff88007b9a7a68>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, hald/1031 # expires at 15856231144038-15856261114038 nsecs [in 4123653207 to 4153623207 nsecs] #1: <ffff880037ba5a68>, hrtimer_wakeup, S:01, hrtimer_start_range_ns, rpcbind/915 # expires at 15871360185906-15871390185905 nsecs [in 19252695075 to 19282695074 nsecs] .expires_next : 9223372036854775807 nsecs .hres_active : 0 .nr_events : 0 .nr_retries : 0 .nr_hangs : 0 .max_hang_time : 0 nsecs .nohz_mode : 0 .idle_tick : 0 nsecs .tick_stopped : 0 .idle_jiffies : 0 .idle_calls : 0 .idle_sleeps : 0 .idle_entrytime : 15852105792015 nsecs .idle_waketime : 0 nsecs .idle_exittime : 0 nsecs .idle_sleeptime : 15827991317141 nsecs .iowait_sleeptime: 3221171737 nsecs .last_jiffies : 0 .next_jiffies : 0 .idle_expires : 0 nsecs jiffies: 4310519631 Tick Device: mode: 0 Broadcast device Clock Event Device: hpet max_delta_ns: 34359738352 min_delta_ns: 5000 mult: 268435456 shift: 32 mode: 2 next_event: 9223372036854775807 nsecs set_next_event: hpet_legacy_next_event set_mode: hpet_legacy_set_mode event_handler: tick_handle_periodic_broadcast tick_broadcast_mask: 00000003 tick_broadcast_oneshot_mask: 00000000 Tick Device: mode: 0 Per CPU device: 0 Clock Event Device: lapic max_delta_ns: 1341975280 min_delta_ns: 2399 mult: 26847583 shift: 32 mode: 1 next_event: 9223372036854775807 nsecs set_next_event: lapic_next_event set_mode: lapic_timer_setup event_handler: tick_handle_periodic Tick Device: mode: 0 Per CPU device: 1 Clock Event Device: lapic max_delta_ns: 1341975280 min_delta_ns: 2399 mult: 26847583 shift: 32 mode: 1 next_event: 9223372036854775807 nsecs set_next_event: lapic_next_event set_mode: lapic_timer_setup event_handler: tick_handle_periodic _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel