diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 7 | ||||
| -rw-r--r-- | arch/x86/xen/time.c | 20 |
2 files changed, 24 insertions, 3 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2b8ee90bb644..2623749ae7a3 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5173,6 +5173,13 @@ with /sys/devices/system/xen_memory/xen_memory0/scrub_pages. Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT. + xen_timer_slop= [X86-64,XEN] + Set the timer slop (in nanoseconds) for the virtual Xen + timers (default is 100000). This adjusts the minimum + delta of virtualized Xen timers, where lower values + improve timer resolution at the expense of processing + more timer interrupts. + xirc2ps_cs= [NET,PCMCIA] Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 6e29794573b7..befbdd8b17f0 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -28,7 +28,7 @@ #include "xen-ops.h" -/* Xen may fire a timer up to this many ns early */ +/* Minimum amount of time until next clock event fires */ #define TIMER_SLOP 100000 static u64 xen_sched_clock_offset __read_mostly; @@ -212,7 +212,7 @@ static int xen_timerop_set_next_event(unsigned long delta, return 0; } -static const struct clock_event_device xen_timerop_clockevent = { +static struct clock_event_device xen_timerop_clockevent __ro_after_init = { .name = "xen", .features = CLOCK_EVT_FEAT_ONESHOT, @@ -273,7 +273,7 @@ static int xen_vcpuop_set_next_event(unsigned long delta, return ret; } -static const struct clock_event_device xen_vcpuop_clockevent = { +static struct clock_event_device xen_vcpuop_clockevent __ro_after_init = { .name = "xen", .features = CLOCK_EVT_FEAT_ONESHOT, @@ -570,3 +570,17 @@ void __init xen_hvm_init_time_ops(void) x86_platform.set_wallclock = xen_set_wallclock; } #endif + +/* Kernel parameter to specify Xen timer slop */ +static int __init parse_xen_timer_slop(char *ptr) +{ + unsigned long slop = memparse(ptr, NULL); + + xen_timerop_clockevent.min_delta_ns = slop; + xen_timerop_clockevent.min_delta_ticks = slop; + xen_vcpuop_clockevent.min_delta_ns = slop; + xen_vcpuop_clockevent.min_delta_ticks = slop; + + return 0; +} +early_param("xen_timer_slop", parse_xen_timer_slop); |