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我碰巧偶然发现了 Queued Spinlock 并想用 C++ 实现。我在谷歌上搜索了一些信息,但无法获得适当的文档。

任何文档/实施提示将不胜感激。

提前致谢

我对迈克尔布朗指出的代码有以下疑问

// represents processor in wait queue of the spinlock
struct qsl_entry
{

// next processor in the queue that is waiting to enter section
qsl_entry* next;

// indicates whether the access to section has been granted to processor
int state;

};

// queued spinlock
struct qsl
{

// the first processor in the queue that is waiting to enter section
qsl_entry* head;

};

// requests access to critical section guarded by the spinlock,
// if the section is already taken it puts processor to wait
// and insert it into queue
// lck - queued lock that used to guard section
// ent - entry that represent processor in queue of the spinlock
void lock_qsl(qsl* lck, qsl_entry* ent)
{
__asm
{
    mov eax, ent;
    mov ebx, lck;

    // prepare queue entry
    mov [eax], 0;
    mov edx, eax;
    mov [eax]qsl_entry.state, 1;

    // store it as the last entry of the queue -- Is this what is line is doing ?
    // ebx contains address of lck & [ ebx ] refers to address pointed by lck & 
    // it is over written to ent. eax now contains the memory the lck was pointing to.
    lock xchg [ebx],eax;

    // if the section available grant access to processor?
    test eax, eax;
    jz enter_section;
        // link new entry with the rest of queue -- really ? are we nt overwritting
        // the next pointer here ?
        mov [eax],edx

        // wait for processor's turn
        wait1:
            pause;
            cmp [edx]qsl_entry.state, 1;
            je wait1;

    enter_section:
 }
}

这个实现是否正确?我怀疑是这样!

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1 回答 1

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此处有问题的代码的作者。首先让我声明代码是正确的。我只是在这里写了更详细的代码解释:http: //kataklinger.com/index.php/queued-spinlocks/

我还有另一种实现,它有点简单,但不如这个好(尽管如此)。我会看看我能不能在某个地方找到它。我找到了。这是包含两种实现的讨论链接:http: //forum.osdev.org/viewtopic.php?f=15 &t=15389

最后一篇文章还有更深入地讨论排队自旋锁的链接:http ://www.cs.rice.edu/~johnmc/papers/tocs91.pdf

是的,我参加聚会有点晚了,但我是几天前的这篇文章,它启发了我写出更好的代码解释。

于 2013-04-06T23:26:49.247 回答