1ea59b5e1a
D. Wythe says: ==================== net/smc: Optimizing performance in short-lived scenarios 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 (Limit 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 (Limit SMC visits when 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 constraint on SMC handshake when handshake workqueue congested, which is the sign of SMC handshake stacking in our opinion. Patch 4/5 (Dynamic control handshake limitation by socket options) This patch allow applications dynamically control the ability of SMC handshake limitation. 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 handshake limitation by netlink) This patch provides a way to get benefit of handshake limitation 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: v1 -> v2: - fix compile warning - fix invalid dependencies in kconfig v2 -> v3: - correct spelling mistakes - fix useless variable declare v3 -> v4 - make smc_tcp_ls_wq be static v4 -> v5 - add dynamic control for SMC auto fallback by socket options - add global configure for SMC auto fallback through netlink v5 -> v6 - move auto fallback to net namespace scope - remove auto fallback attribute in SMC_GEN_SYS_INFO - add independent attributes for auto fallback v6 -> v7 - fix wording and the naming issues, rename 'auto fallback' to handshake limitation. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.