On Thu, 13 Nov 2003, Yung Yi wrote: > Dear all, > > I think that the tcp/ip implementation of the current linux kernel constains > functionality of ssthresh caching, which is commonly used in many operating > systems. Actually, I want to disable this function. However, I cannot figure > out which source code implement this. Could you post some information about > this? Or is there any way to disable this function without changing the > kernel source? The Web100 patch <http://www.web100.org/> has a control for this, though it may be a bit heavyweight if this is all you want. If you want to modify your own kernel, it should be easy. Just disable the initialization in net/ipv4/tcp_input.c:tcp_init_metrics(). The other alternative is to do an "echo 1 > /proc/sys/net/ipv4/route/flush" between connections. It might not be a bad idea to include a control in the stock kernel. Caching ssthresh can cause a significant performance hit in some large window situations. This is more a symptom of the fact that standard congestion control is broken at large windows rather than a fundamental flaw in the connection property caching. But it is a real problem. For experimental purposes, it is also nice to be able to start from a clean state each time, though flushing the cache can accomplish this as well (if it is somewhat inconvenient). -John - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
