On Fri, Nov 25, 2022 at 09:00:26AM +0800, Chao Leng wrote: > The ack timeout retransmission time is affected by the following two > factors: one is packet life time, another is the HCA processing time. > Now the default packet lifetime(CMA_IBOE_PACKET_LIFETIME) is 18. > That means the minimum ack timeout is 2 seconds(2^(18+1)*4us=2.097seconds). > The packet lifetime means the maximum transmission time of packets > on the network, 2 seconds is too long. > Assume the network is a clos topology with three layers, every packet > will pass through five hops of switches. Assume the buffer of every > switch is 128MB and the port transmission rate is 25 Gbit/s, > the maximum transmission time of the packet is 200ms(128MB*5/25Gbit/s). > Add double redundancy, it is less than 500ms. > So change the CMA_IBOE_PACKET_LIFETIME to 16, > the maximum transmission time of the packet will be about 500+ms, > it is long enough. > > Signed-off-by: Chao Leng <lengchao@xxxxxxxxxx> > --- > drivers/infiniband/core/cma.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied to for-next, thanks Jason
