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 1/5 (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 2/5 (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 3/5 (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. Patch 4/5 (Dynamic control SMC auto fallback by socket options) This patch allow applications dynamically control the ability of SMC auto fallback. Since SMC don't support set SMC socket option before, this patch also have to support SMC's owns socket options. Patch 5/5 (Add global configure for auto fallback by netlink) This patch provides a way to get benefit of auto fallback without modifying any code for applications, which is quite useful for most existing applications. 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 -> v1: - fix compile warning - fix invalid dependencies in kconfig v3 -> v2: - correct spelling mistakes - fix useless variable declare v4 -> v3 - make smc_tcp_ls_wq be static v5 -> v4 - add dynamic control for SMC auto fallback by socket options - add global configure for SMC auto fallback through netlink --- D. Wythe (5): net/smc: Make smc_tcp_listen_work() independent net/smc: Limits backlog connections net/smc: Fallback when handshake workqueue congested net/smc: Dynamic control auto fallback by socket options net/smc: Add global configure for auto fallback by netlink include/linux/socket.h | 1 + include/linux/tcp.h | 1 + include/uapi/linux/smc.h | 7 +++ net/ipv4/tcp_input.c | 3 +- net/smc/af_smc.c | 158 ++++++++++++++++++++++++++++++++++++++++++++++- net/smc/smc.h | 12 ++++ net/smc/smc_core.c | 2 + net/smc/smc_netlink.c | 10 +++ 8 files changed, 191 insertions(+), 3 deletions(-) -- 1.8.3.1
