关-为什么关决定只有一个核心

Question

我目前正在测试gwan web服务器，我有一个关于gwan worker的默认设置和CPU核心检测的问题。

在Xen服务器(包含4核Xeon CPU)上运行gwan, gwan.log文件报告仅检测到单核:

'./gwan -w 4' used to override 1 x 1-Core CPU(s)
[Wed May 22 06:54:29 2013 GMT]   using   1 workers 0[01]0
[Wed May 22 06:54:29 2013 GMT]   among   2 threads 0[11]1
[Wed May 22 06:54:29 2013 GMT]   (can't use more threads than CPU Cores)
[Wed May 22 06:54:29 2013 GMT] CPU: 1x Intel(R) Xeon(R) CPU E5506 @ 2.13GHz
[Wed May 22 06:54:29 2013 GMT]  0 id: 0     0
[Wed May 22 06:54:29 2013 GMT]  1 id: 1     1
[Wed May 22 06:54:29 2013 GMT]  2 id: 2     2
[Wed May 22 06:54:29 2013 GMT]  3 id: 3     3
[Wed May 22 06:54:29 2013 GMT] CPU(s):1, Core(s)/CPU:1, Thread(s)/Core:2

任何想法?

谢谢! !

Answer 1

gwan.log文件报告我只有一个核心:

Xen，像许多其他管理程序一样，正在破坏CPUID指令和/proc/cpuinfo Linux内核结构(两者都被G-WAN用于检测CPU内核)。

正如您所看到的，这对于设计用于多核扩展的多线程应用程序来说是一个真正的问题。

"。/gwan -w 4'用于覆盖1个1核CPU

为了避免愚蠢的手动覆盖浪费内存和影响性能，G-WAN检查用户提供的线程数不大于实际的CPU核心数。

这就是为什么你有警告:"(不能使用比CPU内核更多的线程)"。

要绕过此保护和警告，您可以使用-g ("God")模式:

./gwan -g -w 4

这个命令行开关在G-WAN可执行帮助中有文档记录:

./gwan -h
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Usage: gwan [-b -d -g -k -r -t -v -w] [argument]
(grouped options '-bd' are ignored, use '-b -d')
  -b: use the TCP_DEFER_ACCEPT TCP option
      (this is disabling the DoS shield!)
  -d: daemon mode (uses an 'angel' process)
      -d:group:user dumps 'root' privileges
  -g: do not limit worker threads to Cores
      (using more threads than physical Cores
       will lower speed and waste resources)
  -k: (gracefully) kill local gwan processes
      using the pid files of the gwan folder
  -r: run the specified C script (and exit)
      for general-purpose code, not servlets
  -t: store client requests in 'trace' file
      (may be useful to debug/trace attacks)
  -v: return version number and build date
  -w: define the number of worker threads.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Available network interfaces (2):
127.0.0.1 192.168.0.11