On 20/02/2015 15:54, Sebastian Andrzej Siewior wrote: > Usually you see "scheduling while atomic" on -RT and convert them to > raw locks if it is appropriate. > > Bogdan wrote in 2/2 that he needs to limit the number of CPUs in oder > not cause a DoS and large latencies in the host. I haven't seen an > answer to my why question. Because if the conversation leads to > large latencies in the host then it does not look right. > > Each host PIC has a rawlock and does mostly just mask/unmask and the > raw lock makes sure the value written is not mixed up due to > preemption. > This hardly increase latencies because the "locked" path is very short. > If this conversation leads to higher latencies then the locked path is > too long and hardly suitable to become a rawlock. Yes, but large latencies just mean the code has to be rewritten (x86 doesn't anymore do event injection in an atomic regions for example). Until it is, using raw_spin_lock is correct. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
