Merge branch 'cch123:master' into master

wziww · web-flow · commit f3316b85e871 · 2021-08-31T18:19:51.000+08:00
diff --git a/assembly.md b/assembly.md
@@ -999,11 +999,5 @@ go compile -S:
 参考资料[4]需要特别注意，在该 slide 中给出的 callee stack frame 中把 caller 的 return address 也包含进去了，个人认为不是很合适。
 
 
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
 
-
-<!--stackedit_data:
-eyJoaXN0b3J5IjpbMTIzMjkyMzE1MSwtMjY3MTA3MzkxLDEyMz
-I5MjMxNTEsLTg4Mjc1MTcwNiwtMTc0OTAxODUyMiwtMzQ4MTA0
-NjIzLDIwODQwNjM3MjAsLTE1NTYyODU0NDAsMTI2MTcwMTYyMy
-w3NTI0MDk2NTUsMTg4NDQ5NTE5MF19
--->
diff --git a/atomic.md b/atomic.md
@@ -359,4 +359,6 @@ TEXT runtime∕internal∕atomic·Store(SB), NOSPLIT, $0-12
 	MOVL	val+8(FP), AX
 	XCHGL	AX, 0(BX) // 交换指令
 	RET
-```
+```
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/bootstrap.md b/bootstrap.md
@@ -518,4 +518,6 @@ func main() {
 <!--stackedit_data:
 eyJoaXN0b3J5IjpbOTA1MjAxMjAyLC0xNDUzNjA2MjEwLDkwNT
 IwMTIwMiwtMTQ1MzYwNjIxMCwtNTk2NzUzMDMxXX0=
--->
+-->
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/channel.md b/channel.md
@@ -705,3 +705,6 @@ func closechan(c *hchan) {
 Q: 如果有多个channel同时唤醒同一个goroutine，这个并发控制是怎么做的？
 
 Q: 为什么向 channel 发数据的时候，会直接把数据从一个 goroutine 的栈拷贝到另一个 goroutine 的栈？
+
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/context.md b/context.md
@@ -566,3 +566,5 @@ func main() {
 # 总结
 
 ctx 的结构显然是根据代码的执行模型来设计的，虽然设计得比较巧妙，但因为将取消和上下文携带功能混合在一起，在一些情况下还是会给我们埋些比较隐蔽的坑。使用时需要多多注意。
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/defer.md b/defer.md
@@ -160,3 +160,6 @@ A: deferproc 和 deferreturn 是成对出现的，对于编译器的实现来说
 
 https://ieevee.com/tech/2017/11/23/go-panic.html
 
+
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/futex.md b/futex.md
@@ -235,3 +235,6 @@ http://blog.sina.com.cn/s/blog_e59371cc0102v29b.html
 https://www.jianshu.com/p/570a61f08e27
 
 https://eli.thegreenplace.net/2018/basics-of-futexes/
+
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/gc.md b/gc.md
@@ -742,3 +742,5 @@ gc时间，stw时间和响应延迟之间是什么关系
 
 宏观来看gc划分为多少个阶段
 
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/gc_write_barrier.md b/gc_write_barrier.md
@@ -0,0 +1,5 @@
+# GC write barrier 详解
+
+TODO
+
+
diff --git a/generics.md b/generics.md
@@ -40,3 +40,5 @@ cat source.go | genny gen "Something=string"
 
 没有官方的泛型支持，社区怎么搞都是邪道。2021 年 1 月，官方的方案已经基本上成型，并释出了 [draft design](https://go.googlesource.com/proposal/+/refs/heads/master/design/go2draft-type-parameters.md)。
 
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/goroutine.md b/goroutine.md
@@ -7,4 +7,6 @@
 > Written with [StackEdit](https://stackedit.io/).
 <!--stackedit_data:
 eyJoaXN0b3J5IjpbNjQ5NDIwMDBdfQ==
--->
+-->
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/interface.md b/interface.md
@@ -543,3 +543,5 @@ go.itab.*os.File,io.Writer SRODATA dupok size=32
 
 // 下面就是正常流程了
 ```
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/io.md b/io.md
@@ -722,3 +722,5 @@ func Splice(dst, src *FD, remain int64) (written int64, handled bool, sc string,
 
 - https://go-review.googlesource.com/c/go/+/271537/
 - https://zhuanlan.zhihu.com/p/308054212
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/lockfree.md b/lockfree.md
@@ -1,4 +1,6 @@
 # lock free programming in Go
 
 # 参考资料
-https://docs.google.com/presentation/d/1wuNNW-g6v8qizIc_IxAGZTj-49TODKF0TYddTA1VDUo/mobilepresent?slide=id.p
+https://docs.google.com/presentation/d/1wuNNW-g6v8qizIc_IxAGZTj-49TODKF0TYddTA1VDUo/mobilepresent?slide=id.p
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/map.md b/map.md
@@ -1267,3 +1267,5 @@ func (h *hmap) incrnoverflow() {
     }
 }
 ```
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/memory.md b/memory.md
@@ -1396,3 +1396,6 @@ func (p *notInHeap) add(bytes uintptr) *notInHeap {
 ### 堆外内存用法
 
 嗯，堆外内存只是 runtime 自己玩的东西，用户态是使用不了的，属于 runtime 专用的 directive。
+
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/memory_barrier.md b/memory_barrier.md
@@ -126,7 +126,7 @@ mesi 协议解决了多核环境下，内存多层级带来的问题。使得 ca
 
 ## CPU 导致乱序
 
-使用 litmus 进行形式化验证:
+使用 litmus 进行验证:
 
 ```
 cat sb.litmus
@@ -181,6 +181,56 @@ Time SB 0.11
 
 在两个核心上运行汇编指令，意料之外的情况 100w 次中出现了 96 次。虽然很少，但确实是客观存在的情况。
 
+有文档提到，x86 体系的内存序本身比较严格，除了 store-load 以外不存在其它类型的重排，也可以用下列脚本验证:
+
+```
+X86 RW
+{ x=0; y=0; }
+ P0          | P1          ;
+ MOV EAX,[y] | MOV EAX,[x] ;
+ MOV [x],$1  | MOV [y],$1  ;
+locations [x;y;]
+exists (0:EAX=1 /\ 1:EAX=1)
+```
+
+```
+%%%%%%%%%%%%%%%%%%%%%%%%%
+% Results for sb.litmus %
+%%%%%%%%%%%%%%%%%%%%%%%%%
+X86 OOO
+
+{x=0; y=0;}
+
+ P0          | P1          ;
+ MOV EAX,[y] | MOV EAX,[x] ;
+ MOV [x],$1  | MOV [y],$1  ;
+
+locations [x; y;]
+exists (0:EAX=1 /\ 1:EAX=1)
+Generated assembler
+	##START _litmus_P0
+	movl	-4(%rsi,%rcx,4), %eax
+	movl	$1, -4(%rbx,%rcx,4)
+	##START _litmus_P1
+	movl	-4(%rbx,%rcx,4), %eax
+	movl	$1, -4(%rsi,%rcx,4)
+
+Test OOO Allowed
+Histogram (2 states)
+500000:>0:EAX=1; 1:EAX=0; x=1; y=1;
+500000:>0:EAX=0; 1:EAX=1; x=1; y=1;
+No
+
+Witnesses
+Positive: 0, Negative: 1000000
+Condition exists (0:EAX=1 /\ 1:EAX=1) is NOT validated
+Hash=7cdd62e8647b817c1615cf8eb9d2117b
+Observation OOO Never 0 1000000
+Time OOO 0.14
+```
+
+无论运行多少次，Positive 应该都是 0。
+
 ## barrier
 
 从功能上来讲，barrier 有四种:
@@ -519,3 +569,5 @@ https://stackoverflow.com/questions/29880015/lock-prefix-vs-mesi-protocol
 https://github.com/torvalds/linux/blob/master/Documentation/memory-barriers.txt
 
 http://www.overbyte.com.au/misc/Lesson3/CacheFun.html
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/netpoll.md b/netpoll.md
@@ -1355,3 +1355,5 @@ func poll_runtime_pollUnblock(pd *pollDesc) {
     }
 }
 ```
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/panic.md b/panic.md
@@ -295,4 +295,6 @@ func main() {
 	defer panic(2)
 	panic(1)
 }
-```
+```
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/pprof.md b/pprof.md
@@ -771,5 +771,8 @@ runtime 自带的 pprof 已经在数据采集的准确性, 覆盖率, 压力等
 #开源项目 pprof 参考
 [nsq](https://github.com/nsqio/nsq/blob/v1.2.0/nsqd/http.go#L78-L88)
 [etcd](https://github.com/etcd-io/etcd/blob/release-3.4/pkg/debugutil/pprof.go#L23) 采用的是[配置式](https://github.com/etcd-io/etcd/blob/release-3.4/etcd.conf.yml.sample#L76)选择是否开启
+
 # 参考资料
-https://go-review.googlesource.com/c/go/+/299671
+https://go-review.googlesource.com/c/go/+/299671
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/scheduler.md b/scheduler.md
@@ -2348,3 +2348,4 @@ gcMarkDone --> forEachP
 
 当然，这里 entersyscall 和 entersyscallblock 比较特殊，虽然这俩函数的实现中有设置抢占标记，但实际上这两段逻辑是不会被走到的。因为 syscall 执行时是在 m 的 g0 栈上，如果在执行时被抢占，那么会直接 throw，而无法恢复。
 
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/select.md b/select.md
@@ -826,3 +826,5 @@ sclose:
 Q: 如果select多个channel，有一个channel触发了，其他channel的waitlist需要不要主动去除？还是一直在那等着？
 
 A: waitlist 的出列是由 `func (q *waitq) dequeue() *sudog` 函数控制的，每个 sudog 携带了一个 `selectDone` 标志位，通过 `cas` 操作在每次 `dequeue` 的时候「惰性」去除队列中无效的元素
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/semaphore.md b/semaphore.md
@@ -236,7 +236,7 @@ func semacquire1(addr *uint32, lifo bool, profile semaProfileFlags) {
 
     // 高成本的情况:
     //    增加 waiter count 的值
-    //    再尝试调用一次 cansemacquire，成本了就直接返回
+    //    再尝试调用一次 cansemacquire，成功了就直接返回
     //    没成功就把自己作为一个 waiter 入队
     //    sleep
     //    (之后 waiter 的 descriptor 被 signaler 用 dequeue 踢出)
@@ -735,4 +735,6 @@ func notifyListCheck(sz uintptr) {
 func sync_nanotime() int64 {
     return nanotime()
 }
-```
+```
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/signal.md b/signal.md
diff --git a/slice.md b/slice.md
@@ -265,7 +265,7 @@ func main() {
 
 func doSomeHappyThings(arr []int) {
     arr = append(arr, 1)
-    fmt.println(arr, "after append")
+    fmt.Println(arr, "after append")
 }
 ```
 
@@ -338,3 +338,5 @@ func main() {
     sh.Data = (uintptr)(unsafe.Pointer(&b[1]))
     sh.Len = bh.Len - 1
 ```
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/sync.md b/sync.md
@@ -1027,3 +1027,5 @@ Q: 既然被选中了唤醒的那个G，说明这个G就是一定要退出lock
 
 A:
 
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/syscall.md b/syscall.md
@@ -768,4 +768,6 @@ func entersyscall_gcwait() {
 
 3. https://mzh.io/golang-arm64-vdso
 
-4. https://blog.csdn.net/luozhaotian/article/details/79609077
+4. https://blog.csdn.net/luozhaotian/article/details/79609077
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">
diff --git a/timer.md b/timer.md
@@ -779,3 +779,5 @@ func (t *Timer) Reset(d Duration) bool {
 ## 最后
 
 本篇内容主要是讲 Go 的定时器实现，工业界的定时器实现并不只有一种。如果你还想知道其它系统，比如 nginx 里是怎么实现定时器的，可以参考[这一篇](https://www.jianshu.com/p/427dfe8ad3c0)。
+
+<img width="330px"  src="https://xargin.com/content/images/2021/05/wechat.png">

Original file line number	Diff line number	Diff line change
`@@ -742,3 +742,5 @@ gc时间，stw时间和响应延迟之间是什么关系`
`742`	`742`
`743`	`743`	`宏观来看gc划分为多少个阶段`
`744`	`744`
	`745`	`+`
	`746`	`+<img width="330px" src="https://xargin.com/content/images/2021/05/wechat.png">`
-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +# GC write barrier 详解
++
 +TODO
++
++
Original file line number	Diff line number	Diff line change
`@@ -40,3 +40,5 @@ cat source.go \| genny gen "Something=string"`
`40`	`40`
`41`	`41`	`没有官方的泛型支持，社区怎么搞都是邪道。2021 年 1 月，官方的方案已经基本上成型，并释出了 [draft design](https://go.googlesource.com/proposal/+/refs/heads/master/design/go2draft-type-parameters.md)。`
`42`	`42`
	`43`	`+`
	`44`	`+<img width="330px" src="https://xargin.com/content/images/2021/05/wechat.png">`