* TSC can be unstable due to cpufreq or due to unsynced TSCs
*/
static int __read_mostly tsc_unstable;
+static unsigned int __initdata tsc_early_khz;
static DEFINE_STATIC_KEY_FALSE(__use_tsc);
struct cyc2ns {
struct cyc2ns_data data[2]; /* 0 + 2*16 = 32 */
- seqcount_t seq; /* 32 + 4 = 36 */
+ seqcount_latch_t seq; /* 32 + 4 = 36 */
}; /* fits one cacheline */
static DEFINE_PER_CPU_ALIGNED(struct cyc2ns, cyc2ns);
+static int __init tsc_early_khz_setup(char *buf)
+{
+ return kstrtouint(buf, 0, &tsc_early_khz);
+}
+early_param("tsc_early_khz", tsc_early_khz_setup);
+
__always_inline void cyc2ns_read_begin(struct cyc2ns_data *data)
{
int seq, idx;
preempt_disable_notrace();
do {
- seq = this_cpu_read(cyc2ns.seq.sequence);
+ seq = this_cpu_read(cyc2ns.seq.seqcount.sequence);
idx = seq & 1;
data->cyc2ns_offset = this_cpu_read(cyc2ns.data[idx].cyc2ns_offset);
data->cyc2ns_mul = this_cpu_read(cyc2ns.data[idx].cyc2ns_mul);
data->cyc2ns_shift = this_cpu_read(cyc2ns.data[idx].cyc2ns_shift);
- } while (unlikely(seq != this_cpu_read(cyc2ns.seq.sequence)));
+ } while (unlikely(seq != this_cpu_read(cyc2ns.seq.seqcount.sequence)));
}
__always_inline void cyc2ns_read_end(void)
{
struct cyc2ns *c2n = this_cpu_ptr(&cyc2ns);
- seqcount_init(&c2n->seq);
+ seqcount_latch_init(&c2n->seq);
__set_cyc2ns_scale(tsc_khz, smp_processor_id(), rdtsc());
}
for_each_possible_cpu(cpu) {
if (cpu != this_cpu) {
- seqcount_init(&c2n->seq);
+ seqcount_latch_init(&c2n->seq);
c2n = per_cpu_ptr(&cyc2ns, cpu);
c2n->data[0] = data[0];
c2n->data[1] = data[1];
if (early) {
cpu_khz = x86_platform.calibrate_cpu();
- tsc_khz = x86_platform.calibrate_tsc();
+ if (tsc_early_khz)
+ tsc_khz = tsc_early_khz;
+ else
+ tsc_khz = x86_platform.calibrate_tsc();
} else {
/* We should not be here with non-native cpu calibration */
WARN_ON(x86_platform.calibrate_cpu != native_calibrate_cpu);