- YSRossi·Last edited by YSRossi on Jun 22, 2023Linked with GitHubContributed by
2023q1 Homework7 (ktcp)
contributed by < YSRossi >
開發環境
$ gcc --version
gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Address sizes: 48 bits physical, 48 bits virtual
Byte Order: Little Endian
CPU(s): 8
On-line CPU(s) list: 0-7
Vendor ID: AuthenticAMD
Model name: AMD FX-8320E Eight-Core Processor
CPU family: 21
Model: 2
Thread(s) per core: 2
Core(s) per socket: 4
Socket(s): 1
Stepping: 0
Frequency boost: enabled
CPU max MHz: 3200.0000
CPU min MHz: 1400.0000
BogoMIPS: 6429.64
開發紀錄
使用 Ftrace 觀察 kHTTPd
Ftrace 原始 kHTTPd 結果
$ sudo cat /sys/kernel/debug/tracing/trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
5) | http_server_worker [khttpd]() {
5) | kernel_sigaction() {
5) 0.744 us | _raw_spin_lock_irq();
5) 0.560 us | _raw_spin_unlock_irq();
5) 3.674 us | }
5) | kernel_sigaction() {
5) 0.553 us | _raw_spin_lock_irq();
5) 0.544 us | _raw_spin_unlock_irq();
5) 2.878 us | }
5) | kmalloc_trace() {
5) | __kmem_cache_alloc_node() {
5) 0.676 us | __cond_resched();
5) 0.599 us | should_failslab();
5) 4.725 us | }
5) 5.874 us | }
5) 0.567 us | http_parser_init [khttpd]();
5) 0.563 us | kthread_should_stop();
5) | http_server_recv.constprop.0 [khttpd]() {
5) | kernel_recvmsg() {
5) | sock_recvmsg() {
5) 2.242 us | security_socket_recvmsg();
5) 7.902 us | inet_recvmsg();
5) + 12.048 us | }
5) + 13.354 us | }
5) + 14.520 us | }
5) | kernel_sock_shutdown() {
5) | inet_shutdown() {
5) | lock_sock_nested() {
5) 0.540 us | __cond_resched();
5) 0.601 us | _raw_spin_lock_bh();
5) 0.792 us | _raw_spin_unlock_bh();
5) 4.161 us | }
5) | tcp_shutdown() {
5) 1.042 us | tcp_set_state();
5) ! 168.549 us | tcp_send_fin();
5) ! 171.821 us | }
5) | sock_def_wakeup() {
5) 0.562 us | __rcu_read_lock();
5) 0.569 us | __rcu_read_unlock();
5) 2.945 us | }
5) | release_sock() {
5) 0.562 us | _raw_spin_lock_bh();
5) + 25.014 us | __release_sock();
5) 0.601 us | tcp_release_cb();
5) 0.833 us | _raw_spin_unlock_bh();
5) + 29.973 us | }
5) ! 211.963 us | }
5) ! 213.299 us | }
3) | http_server_worker [khttpd]() {
5) | sock_release() {
5) | inet_release() {
3) | kernel_sigaction() {
3) 0.374 us | _raw_spin_lock_irq();
5) 0.639 us | ip_mc_drop_socket();
3) 0.221 us | _raw_spin_unlock_irq();
3) 1.805 us | }
5) | tcp_close() {
3) | kernel_sigaction() {
3) 0.228 us | _raw_spin_lock_irq();
5) 1.423 us | lock_sock_nested();
3) 0.229 us | _raw_spin_unlock_irq();
3) 1.230 us | }
3) | kmalloc_trace() {
3) | __kmem_cache_alloc_node() {
3) 0.353 us | __cond_resched();
5) 9.202 us | __tcp_close();
3) 0.220 us | should_failslab();
3) 1.555 us | }
3) 2.018 us | }
3) 0.235 us | http_parser_init [khttpd]();
3) 0.228 us | kthread_should_stop();
3) | http_server_recv.constprop.0 [khttpd]() {
3) | kernel_recvmsg() {
3) | sock_recvmsg() {
3) 1.047 us | security_socket_recvmsg();
3) 5.441 us | inet_recvmsg();
5) 1.437 us | release_sock();
3) 7.222 us | }
3) 7.689 us | }
3) 8.213 us | }
3) | http_parser_execute [khttpd]() {
3) 0.244 us | http_parser_callback_message_begin [khttpd]();
5) 7.970 us | sk_free();
3) 0.458 us | parse_url_char [khttpd]();
3) 0.310 us | http_parser_callback_request_url [khttpd]();
3) 0.217 us | http_parser_callback_header_field [khttpd]();
3) 0.214 us | http_parser_callback_header_value [khttpd]();
3) 0.222 us | http_parser_callback_headers_complete [khttpd]();
3) 0.229 us | http_message_needs_eof [khttpd]();
3) 0.234 us | http_should_keep_alive [khttpd]();
3) | http_parser_callback_message_complete [khttpd]() {
3) 0.223 us | http_should_keep_alive [khttpd]();
3) | _printk() {
3) + 13.850 us | vprintk();
5) + 22.892 us | }
5) + 25.432 us | }
5) 0.593 us | module_put();
5) | iput() {
5) 0.579 us | _raw_spin_lock();
5) 0.550 us | _raw_spin_unlock();
5) | evict() {
5) 1.672 us | inode_wait_for_writeback();
5) 1.120 us | truncate_inode_pages_final();
5) 1.026 us | clear_inode();
5) 0.567 us | _raw_spin_lock();
3) + 14.461 us | }
5) 0.690 us | wake_up_bit();
3) | http_server_send.isra.0 [khttpd]() {
5) 0.546 us | _raw_spin_unlock();
3) + 52.964 us | kernel_sendmsg();
5) 6.136 us | destroy_inode();
5) + 16.597 us | }
5) + 20.794 us | }
5) + 49.266 us | }
5) | kfree() {
5) 0.635 us | __kmem_cache_free();
5) 2.001 us | }
5) ! 301.312 us | }
3) + 53.702 us | }
3) + 70.234 us | }
3) + 78.295 us | }
3) 0.271 us | http_should_keep_alive [khttpd]();
3) | kernel_sock_shutdown() {
3) | inet_shutdown() {
3) | lock_sock_nested() {
3) 0.231 us | __cond_resched();
3) 0.269 us | _raw_spin_lock_bh();
3) 0.328 us | _raw_spin_unlock_bh();
3) 1.710 us | }
3) | tcp_shutdown() {
3) 0.334 us | tcp_set_state();
3) + 21.255 us | tcp_send_fin();
3) + 22.467 us | }
3) | sock_def_wakeup() {
3) 0.222 us | __rcu_read_lock();
3) 0.236 us | __rcu_read_unlock();
3) 4.224 us | }
3) | release_sock() {
3) 0.233 us | _raw_spin_lock_bh();
3) 0.224 us | tcp_release_cb();
3) 0.339 us | _raw_spin_unlock_bh();
3) 1.669 us | }
3) + 31.272 us | }
3) + 31.804 us | }
3) | sock_release() {
3) | inet_release() {
3) 0.216 us | ip_mc_drop_socket();
3) | tcp_close() {
3) 0.571 us | lock_sock_nested();
3) 1.498 us | __tcp_close();
3) 0.581 us | release_sock();
3) 3.505 us | }
3) 4.421 us | }
3) 0.251 us | module_put();
3) | iput() {
3) 0.338 us | _raw_spin_lock();
3) 0.228 us | _raw_spin_unlock();
3) | evict() {
3) 0.612 us | inode_wait_for_writeback();
3) 0.541 us | truncate_inode_pages_final();
3) 0.519 us | clear_inode();
3) 0.218 us | _raw_spin_lock();
3) 0.295 us | wake_up_bit();
3) 0.217 us | _raw_spin_unlock();
3) 2.220 us | destroy_inode();
3) 7.052 us | }
3) 8.712 us | }
3) + 14.356 us | }
3) | kfree() {
3) 0.254 us | __kmem_cache_free();
3) 0.703 us | }
3) ! 144.009 us | }
Ftrace CMWQ + kHTTPd 結果
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
3) | http_server_worker_CMWQ [khttpd]() {
3) | kernel_sigaction() {
3) 0.944 us | _raw_spin_lock_irq();
3) 0.549 us | _raw_spin_unlock_irq();
3) 3.686 us | }
3) | kernel_sigaction() {
3) 0.505 us | _raw_spin_lock_irq();
3) 0.525 us | _raw_spin_unlock_irq();
3) 2.628 us | }
3) | kmalloc_trace() {
3) | __kmem_cache_alloc_node() {
3) 0.588 us | __cond_resched();
3) 0.589 us | should_failslab();
3) 4.440 us | }
3) 5.607 us | }
3) 0.583 us | http_parser_init [khttpd]();
3) | kernel_recvmsg() {
3) | sock_recvmsg() {
3) | security_socket_recvmsg() {
3) 1.393 us | apparmor_socket_recvmsg();
3) 2.558 us | }
3) | inet_recvmsg() {
3) 6.998 us | tcp_recvmsg();
3) 8.240 us | }
3) + 12.681 us | }
3) + 13.952 us | }
3) | kernel_sock_shutdown() {
3) | inet_shutdown() {
3) | lock_sock_nested() {
3) 0.530 us | __cond_resched();
3) 0.510 us | _raw_spin_lock_bh();
3) 0.844 us | _raw_spin_unlock_bh();
3) 3.947 us | }
3) | tcp_shutdown() {
3) 0.969 us | tcp_set_state();
3) ! 153.584 us | tcp_send_fin();
3) ! 156.750 us | }
3) | sock_def_wakeup() {
3) 0.587 us | __rcu_read_lock();
3) 0.575 us | __rcu_read_unlock();
3) 3.094 us | }
3) | release_sock() {
3) 0.512 us | _raw_spin_lock_bh();
3) + 24.762 us | __release_sock();
3) 0.559 us | tcp_release_cb();
3) 0.832 us | _raw_spin_unlock_bh();
3) + 29.627 us | }
3) ! 196.324 us | }
3) ! 197.551 us | }
3) | sock_release() {
3) | inet_release() {
3) 0.569 us | ip_mc_drop_socket();
3) | tcp_close() {
3) 1.312 us | lock_sock_nested();
3) 9.004 us | __tcp_close();
3) 1.447 us | release_sock();
3) 7.757 us | sk_free();
3) + 22.409 us | }
3) + 24.835 us | }
3) 0.570 us | module_put();
3) | iput() {
3) 0.572 us | _raw_spin_lock();
3) 0.546 us | _raw_spin_unlock();
3) | evict() {
3) 1.555 us | inode_wait_for_writeback();
3) 1.207 us | truncate_inode_pages_final();
3) 1.085 us | clear_inode();
3) 0.564 us | _raw_spin_lock();
3) 0.784 us | wake_up_bit();
3) 0.523 us | _raw_spin_unlock();
3) 6.016 us | destroy_inode();
3) + 16.321 us | }
3) + 20.081 us | }
3) + 48.087 us | }
3) | kfree() {
3) 0.570 us | __kmem_cache_free();
3) 1.830 us | }
3) ! 281.959 us | }
3) | http_server_worker_CMWQ [khttpd]() {
3) | kernel_sigaction() {
3) 0.596 us | _raw_spin_lock_irq();
3) 0.571 us | _raw_spin_unlock_irq();
3) 2.960 us | }
3) | kernel_sigaction() {
3) 0.634 us | _raw_spin_lock_irq();
3) 0.604 us | _raw_spin_unlock_irq();
3) 2.940 us | }
3) | kmalloc_trace() {
3) | __kmem_cache_alloc_node() {
3) 0.515 us | __cond_resched();
3) 0.493 us | should_failslab();
3) 3.327 us | }
3) 4.432 us | }
3) 0.555 us | http_parser_init [khttpd]();
3) | kernel_recvmsg() {
3) | sock_recvmsg() {
3) | security_socket_recvmsg() {
3) 1.079 us | apparmor_socket_recvmsg();
3) 2.153 us | }
3) | inet_recvmsg() {
3) + 63.993 us | tcp_recvmsg();
3) + 65.393 us | }
3) + 69.175 us | }
3) + 70.229 us | }
3) | http_parser_execute [khttpd]() {
3) 0.715 us | http_parser_callback_message_begin [khttpd]();
3) 0.800 us | parse_url_char [khttpd]();
3) 0.635 us | http_parser_callback_request_url [khttpd]();
3) 0.587 us | http_parser_callback_header_field [khttpd]();
3) 0.548 us | http_parser_callback_header_value [khttpd]();
3) 0.550 us | http_parser_callback_headers_complete [khttpd]();
3) 0.506 us | http_message_needs_eof [khttpd]();
3) 0.531 us | http_should_keep_alive [khttpd]();
3) | http_parser_callback_message_complete [khttpd]() {
3) 0.569 us | http_should_keep_alive [khttpd]();
3) | http_server_send.isra.0 [khttpd]() {
3) ! 108.584 us | kernel_sendmsg();
3) ! 110.310 us | }
3) ! 113.065 us | }
3) ! 128.950 us | }
3) 0.579 us | http_should_keep_alive [khttpd]();
3) | kernel_sock_shutdown() {
3) | inet_shutdown() {
3) | lock_sock_nested() {
3) 0.518 us | __cond_resched();
3) 0.555 us | _raw_spin_lock_bh();
3) 0.746 us | _raw_spin_unlock_bh();
3) 3.922 us | }
3) | tcp_shutdown() {
3) 0.836 us | tcp_set_state();
3) + 64.025 us | tcp_send_fin();
3) + 66.696 us | }
3) | sock_def_wakeup() {
3) 0.501 us | __rcu_read_lock();
3) 0.594 us | __rcu_read_unlock();
3) 2.812 us | }
3) | release_sock() {
3) 0.511 us | _raw_spin_lock_bh();
3) 0.493 us | tcp_release_cb();
3) 0.737 us | _raw_spin_unlock_bh();
3) 4.004 us | }
3) + 80.010 us | }
3) + 81.076 us | }
3) | sock_release() {
3) | inet_release() {
3) 0.505 us | ip_mc_drop_socket();
3) | tcp_close() {
3) 1.352 us | lock_sock_nested();
3) 3.370 us | __tcp_close();
3) 1.392 us | release_sock();
3) 8.174 us | }
3) + 10.206 us | }
3) 0.553 us | module_put();
3) | iput() {
3) 0.662 us | _raw_spin_lock();
3) 0.510 us | _raw_spin_unlock();
3) | evict() {
3) 1.404 us | inode_wait_for_writeback();
3) 0.853 us | truncate_inode_pages_final();
3) 0.960 us | clear_inode();
3) 0.525 us | _raw_spin_lock();
3) 0.587 us | wake_up_bit();
3) 1.395 us | _raw_spin_unlock();
3) 4.778 us | destroy_inode();
3) + 14.774 us | }
3) + 18.100 us | }
3) + 30.975 us | }
3) | kfree() {
3) 0.582 us | __kmem_cache_free();
3) 1.689 us | }
3) ! 331.912 us | }
khttpd 執行流程
In multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user.
khttp_init -> http_server_daemon -> http_server_worker
khttp_init
建立 socket 等待連線，建立執行緒執行 http_server_daemon
http_server_daemon
等待來自 client 的連線請求 kernel_accept，建立執行緒執行 http_server_worker
http_server_worker
解析收到的資料，執行指定任務
| requests/sec | |
|---|---|
| 原始 khttpd | 17256.942 |
| 原始 khttpd 移除 pr_info | 17901.643 |
| 引入 CMWQ 的 khttpd 移除 pr_info | 38070.105 |
This attribute, attached to a variable or structure field, means that the variable or field is meant to be possibly unused. GCC does not produce a warning for this variable or field.
workqueue_struct
struct workqueue_struct {
struct cpu_workqueue_struct *cpu_wq; //該數組每一項對應系統中的一個處理器
struct list_head list;
const char *name;
int singlethread;
int freezeable; /* Freeze threads during suspend */
int rt;
#ifdef CONFIG_LOCKDEP
struct lockdep_map lockdep_map;
#endif
}
work_struct
struct work_struct {
atomic_long_t data;
struct list_head entry;
work_func_t func; // 要處理的函數
}
一個 work_struct 實例代表一個"工作"，工作包含想要執行的任務。
測試 HTTP keep-alive 模式
輸入下指令進行連線
$ telnet localhost 8081
輸入 GET / HTTP/1.0 （注意：請求訊息輸入完後要多按一次 Enter）
HTTP/1.1 200 OK
Server: khttpd
Content-Type: text/plain
Content-Length: 12
Connection: Close
輸入 GET / HTTP/1.1
HTTP/1.1 200 OK
Server: khttpd
Content-Type: text/plain
Content-Length: 12
Connection: Keep-Alive
根據回傳的 Connection 欄位得知，kHTTPd 本身有 keep-alive 的功能。
Read more
Linux 核心專題: 以 eBPF 建構 TCP 伺服器
執行人: YSRossi專題解說錄影
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