From: "D. Wythe" <alibuda@xxxxxxxxxxxxxxxxx> This patch set aims to optimizing performance of SMC in short-lived links scenarios, which is quite unsatisfactory right now. In our benchmark, we test it with follow scripts: ./wrk -c 10000 -t 4 -H 'Connection: Close' -d 20 http://smc-server Current performance figures like that: Running 20s test @ http://11.213.45.6 4 threads and 10000 connections 4956 requests in 20.06s, 3.24MB read Socket errors: connect 0, read 0, write 672, timeout 0 Requests/sec: 247.07 Transfer/sec: 165.28KB There are many reasons for this phenomenon, this patch set doesn't solve it all though, but it can be well alleviated with it in. Patch 1/3 (Make smc_tcp_listen_work() independent) : Separate smc_tcp_listen_work() from smc_listen_work(), make them independent of each other, the busy SMC handshake can not affect new TCP connections visit any more. Avoid discarding a large number of TCP connections after being overstock, which is undoubtedly raise the connection establishment time. Patch 2/3 (Limits SMC backlog connections): Since patch 1 has separated smc_tcp_listen_work() from smc_listen_work(), an unrestricted TCP accept have come into being. This patch try to put a limit on SMC backlog connections refers to implementation of TCP. Patch 3/3 (Fallback when SMC handshake workqueue congested): Considering the complexity of SMC handshake right now, in short-lived links scenarios, this may not be the main scenario of SMC though, it's performance is still quite poor. This Patch try to provide auto fallback case when SMC handshake workqueue congested, which is the sign of SMC handshake stacking in our opinion. Of course, it's optional. After this patch set, performance figures like that: Running 20s test @ http://11.213.45.6 4 threads and 10000 connections 693253 requests in 20.10s, 452.88MB read Requests/sec: 34488.13 Transfer/sec: 22.53MB That's a quite well performance improvement, about to 6 to 7 times in my environment. --- changelog: v2: fix compile warning and invalid dependencies for kconfig --- D. Wythe (3): net/smc: Make smc_tcp_listen_work() independent net/smc: Limits backlog connections net/smc: Fallback when handshake workqueue congested include/linux/tcp.h | 1 + net/ipv4/tcp_input.c | 3 +- net/smc/Kconfig | 12 ++++++++ net/smc/af_smc.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++-- net/smc/smc.h | 5 ++++ 5 files changed, 96 insertions(+), 3 deletions(-) -- 1.8.3.1
