* Bits needed to read the hw events in user-space. * --- * u32 seq, time_mult, time_shift, index, width; * u64 count, enabled, running; * u64 cyc, time_offset; * s64 pmc = 0; * * do { * seq = pc->lock; * barrier() * * enabled = pc->time_enabled; * running = pc->time_running; * * if (pc->cap_usr_time && enabled != running) { * cyc = rdtsc(); * time_offset = pc->time_offset; * time_mult = pc->time_mult; * time_shift = pc->time_shift; * } * * index = pc->index; * count = pc->offset; * if (pc->cap_user_rdpmc && index) { * width = pc->pmc_width; * pmc = rdpmc(index - 1); * } * * barrier(); * } while (pc->lock != seq); * --- * NOTE: for obvious reason this only works on self-monitoring * processes. *//** seqlock for synchronization