I just see that this patch went into mainline. [PATCH] posix-timers: high-resolution CPU clocks for POSIX clock_* syscalls
This patch provides support for thread and process CPU time clocks in the .... /* + * This is called on clock ticks and on context switches. + * Bank in p->sched_time the ns elapsed since the last tick or switch. + */ +static inline void update_cpu_clock(task_t *p, runqueue_t *rq, + unsigned long long now) +{ + unsigned long long last = max(p->timestamp, rq->timestamp_last_tick); + p->sched_time += now - last; +} + called from schedule(). The problem with this is that it completely messes up the register allocation for i386 schedule() because it does long long arithmetic. This causes gcc to spill everything else because it needs four registers, and i386 only has 6 usable ones. I think a critical path like the scheduler needs a little bit more care. Also it is totally unclear if this obscure POSIX feature is really worth making schedule() slower. I think not. In case it is kept it should be done in a way that doesn't impact i386 unduly e.g. by avoiding long long arithmetic here and making sure fast paths stay fast. I would propose to back this patch out again until this is resolved. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/