#perf stat -e branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,stalled-cycles-backend,stalled-cycles-frontend,alignment-faults,bpf-output,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-dcache-store-misses,L1-dcache-stores,L1-icache-load-misses,L1-icache-loads,branch-load-misses,branch-loads,dTLB-load-misses,dTLB-loads,iTLB-load-misses,iTLB-loads ./aftersort 11.44 sum = 314931600000
#perf stat -e branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,stalled-cycles-backend,stalled-cycles-frontend,alignment-faults,bpf-output,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-icache-load-misses,L1-icache-loads,LLC-load-misses,LLC-loads,branch-load-misses,branch-loads,dTLB-load-misses,dTLB-loads,iTLB-load-misses,iTLB-loads ./aftersort 8.20237 sum = 314931600000
#perf stat -e branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,stalled-cycles-backend,stalled-cycles-frontend,alignment-faults,bpf-output,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-icache-load-misses,L1-icache-loads,LLC-load-misses,LLC-loads,branch-load-misses,branch-loads,dTLB-load-misses,dTLB-loads,iTLB-load-misses,iTLB-loads ./beforesort 16.8872 sum = 314931600000
#perf stat -e branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,alignment-faults,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-dcache-store-misses,L1-dcache-stores,L1-icache-load-misses,L1-icache-loads,branch-load-misses,branch-loads,dTLB-load-misses,iTLB-load-misses ./aftersort 16.63 sum = 314931600000
#perf stat -e branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,alignment-faults,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-dcache-store-misses,L1-dcache-stores,L1-icache-load-misses,L1-icache-loads,branch-load-misses,branch-loads,dTLB-load-misses,iTLB-load-misses ./beforesort 39.8 sum = 314931600000
#perf stat -e branch-instructions,branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,ref-cycles,alignment-faults,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-dcache-stores,L1-icache-load-misses,LLC-load-misses,LLC-loads,LLC-store-misses,LLC-stores,branch-load-misses,branch-loads,dTLB-load-misses,dTLB-loads,dTLB-store-misses,dTLB-stores,iTLB-load-misses,iTLB-loads,node-load-misses,node-loads,node-store-misses,node-stores ./aftersort 9.77 sum = 314931600000
排序后去掉了 branch miss 差异，M710 比 intel 快了 10%，只要是因为主频的差异
on 8269 3.2GHz
1 2 3 4 5 6 7 8 9 10 11 12 13 14
#perf stat -e branch-instructions,branch-misses,cpu-cycles,instructions,branch-load-misses,branch-loads,task-clock,cpu-clock ./beforesort 22.96 sum = 314931600000
#perf stat -e branch-instructions,branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,ref-cycles,alignment-faults,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-dcache-stores,L1-icache-load-misses,LLC-load-misses,LLC-loads,LLC-store-misses,LLC-stores,branch-load-misses,branch-loads,dTLB-load-misses,dTLB-loads,dTLB-store-misses,dTLB-stores,iTLB-load-misses,iTLB-loads,node-load-misses,node-loads,node-store-misses,node-stores ./beforesort 2.94 sum = 314931600000
#perf stat -e branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,stalled-cycles-backend,stalled-cycles-frontend,alignment-faults,bpf-output,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-icache-load-misses,L1-icache-loads,LLC-load-misses,LLC-loads,branch-load-misses,branch-loads,dTLB-load-misses,dTLB-loads,iTLB-load-misses,iTLB-loads ./beforesort 1.19468 sum = 314931600000
#perf stat -e branch-misses,bus-cycles,cache-misses,cache-references,cpu-cycles,instructions,stalled-cycles-backend,stalled-cycles-frontend,alignment-faults,bpf-output,context-switches,cpu-clock,cpu-migrations,dummy,emulation-faults,major-faults,minor-faults,page-faults,task-clock,L1-dcache-load-misses,L1-dcache-loads,L1-icache-load-misses,L1-icache-loads,LLC-load-misses,LLC-loads,branch-load-misses,branch-loads,dTLB-load-misses,dTLB-loads,iTLB-load-misses,iTLB-loads ./aftersort 1.1949 sum = 314931600000
如上图的上面部分代表通常情况下的简单代码布局。如果区域 B（这里是内联函数 inlfct 生成的代码）经常由于条件 I 被跳过，而不会执行，处理器的预取将拉入很少使用的包含块 B 的高速缓存行。使用块重新排序可以改变这种局面，改变之后的效果可以在图的下半部分看到。经常执行的代码在内存中是线性的，而很少执行的代码被移动到不会损害预取和 L1i 效率的位置。
举个例子，如果一个线程运行过程中，必须要等到一些数据加载到缓存中以后才能继续执行，此时 CPU 就可以切换到另一个线程，去执行其他指令，而不用去处于空闲状态，等待当前线程的数据加载完毕。通常，一个传统的处理器在线程之间切换，可能需要几万个时钟周期。而一个具有 HT 超线程技术的处理器只需要 1 个时钟周期。因此就大大减小了线程之间切换的成本，从而最大限度地让处理器满负荷运转。
ARM芯片基本不做超线程，另外请思考为什么有了应用层的多线程切换还需要CPU层面的超线程？
超线程(Hyper-Threading)物理实现: 在CPU内部增加寄存器等硬件设施，但是ALU、译码器等关键单元还是共享。在一个物理 CPU 核心内部，会有双份的 PC 寄存器、指令寄存器乃至条件码寄存器。超线程的目的，是在一个线程 A 的指令，在流水线里停顿的时候，让另外一个线程去执行指令。因为这个时候，CPU 的译码器和 ALU 就空出来了，那么另外一个线程 B，就可以拿来干自己需要的事情。这个线程 B 可没有对于线程 A 里面指令的关联和依赖。
#程序员的螺丝刀# tc（traffic control） 模拟丢包率、设置时延等等简直太香了。我不知道不会用的程序员是怎么搞的 延时设置： give packets from eth0 a delay of 2ms bash$ tc qdisc add dev eth0 root netem delay 2ms
change the delay to 300ms bash$ tc qdisc change dev eth0 root netem delay 3ms
display eth0 delay setting bash$ tc qdisc show dev eth0
比较不忍看到大多新同事刚一进来被丢到了错误的位置上，新同事还不敢拒绝。第一种是要面对新公司一大坨内部产品和术语，没有人带，这种太不人道；第二种因为错配而要面对新技术领域，大体还是能 Google 到，不过对他们压力太大，这种我一般会带一次，再多也没精力，毕竟跨了团队；几个月下来新同事肯定觉得被 PUA了
客户端从 server 拖数据，偶尔会出现 TCP 连接卡死，卡死的现象就是 server 不遵循 TCP 重传逻辑，客户端不停地发 dup ack，但是服务端不响应这些dup ack仍然发一些新的包(从server抓包可以看到)，一会后服务端不再发任何新包，也不响应dup ack 来传丢掉的包，进入永久静默，最终连接闲置过久被reset，客户端抛连接异常.
Client MySQL JDBC 协议拉取 Server 3306端口 数据，频繁出现卡死与超时，Client端Java 报错：Application was streaming results when the connection failed. Consider raising value of ‘net_write_timeout’ on the server. - com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Application was streaming results when the connection failed. Consider raising value of ‘net_write_timeout’ on the server.
Hi Eric, I now have a packetdrill test that started failing (see below). Admittedly, a bit weird test with the SO_SNDBUF forced so low. Nevertheless, previously this test would pass, now it stalls after the write() because tcp_fragment() returns -ENOMEM. Your commit-message mentions that this could trigger when one sets SO_SNDBUF low. But, here we have a complete stall of the connection and we never recover. I don’t know if we care about this, but there it is :-)
The table and graph below show the number of HTTP requests for varying numbers of CPUs and varying request sizes, in kilobytes (KB).
CPUs
0 KB
1 KB
10 KB
100 KB
1
145,551
74,091
54,684
33,125
2
249,293
131,466
102,069
62,554
4
543,061
261,269
207,848
88,691
8
1,048,421
524,745
392,151
91,640
16
2,001,846
972,382
663,921
91,623
32
3,019,182
1,316,362
774,567
91,640
36
3,298,511
1,309,358
764,744
91,655
RPS for HTTPS Requests
HTTPS RPS is lower than HTTP RPS for the same provisioned bare‑metal hardware because the data encryption and decryption necessary to secure data transmitted between machines is computationally expensive.
Nonetheless, continued advances in Intel architecture – resulting in servers with faster processors and better memory management – mean that the performance of software for CPU‑bound encryption tasks continually improves compared to dedicated hardware encryption devices.
Though RPS for HTTPS are roughly one‑quarter less than for HTTP at the 16‑CPU mark, “throwing hardware at the problem” – in the form of additional CPUs – is more effective than for HTTP, for the more commonly used file sizes and all the way up to 36 CPUs.
include /etc/nginx/mime.types; default_type application/octet-stream;
# Load modular configuration files from the /etc/nginx/conf.d directory. # See http://nginx.org/en/docs/ngx_core_module.html#include # for more information. include /etc/nginx/conf.d/*.conf;
//sendfile on ,tcp_nopush on, quickack on; QPS 46万 #ip route change 172.16.0.0/24 dev eth0 quickack 1
#ip route default via 172.16.0.253 dev eth0 169.254.0.0/16 dev eth0 scope link metric 1002 172.16.0.0/24 dev eth0 scope link quickack 1 192.168.5.0/24 dev docker0 proto kernel scope link src 192.168.5.1
When set indicates to always queue non-full frames. Later the user clears this option and we transmit any pending partial frames in the queue. This is meant to be used alongside sendfile() to get properly filled frames when the user (for example) must write out headers with a write() call first and then use sendfile to send out the data parts. TCP_CORK can be set together with TCP_NODELAY and it is stronger than TCP_NODELAY.
location / { return 200 '<!DOCTYPE html><h2>null!</h2>\n'; #直接内存返回，不读磁盘文件，避免文件锁 # because default content-type is application/octet-stream, # browser will offer to "save the file"... # if you want to see reply in browser, uncomment next line # add_header Content-Type text/plain; root /usr/share/nginx/html; index index.html index.htm; }
![[中国赞]](/images/951413iMgBlog/2018new_zhongguozan_org.png)
，比我厉害1万倍
