Hello, Mindaugas said: > Can you explain what the actual problem M_WAIT causes i.e. how would > it "freeze network stack"?
In M_WAIT case, m_reclaim() will run and run until get mbuf cluster if mclpool limit reached. If m_reclaim() repeatedly but cannot to get new mbuf cluster, m_clget() will not return. network stacks using mbufs is use with M_DONTWAIT, but it will failed to get new mbuf cluster in this case. "freeze" means that. Generally NMBCLUSTERS is enough and SB_MAX is small, the problem is rarely caused. It depends parameter configuration, I think. In other words, to cause this problem, - many packets receives from the network, it will read by userland - userland program sends many packets, but not read packet from the stack - and mclpool limit reached. - no one calls pool_put() In M_DONTWAIT case, M_EXT flag is result of m_clget(). code of checking M_EXT is already prepared, but didn't used it with M_WAIT. I think this is careless miss. Thanks. -- Masaru OKI <o...@netbsd.org>
