> No it isn't, it has a fixed number of yields, which has a very different duration on various CPUs
You say this with zero data.
I know that yielding 40 times is optimal for WebKit because I measured it. In fact it was re-measured many times because folks like you would doubt that it could’ve optimal, suggest something different, and then again the 40 yields would be shown to be optimal.
> And no if you read the code, they do spin. Worse, they actually yield the thread before properly parking.
Threads wait if the lock is not available immediately-ish.
Yes, they spin by yielding. Spinning by pausing or doing anything else results in worse performance. We measured this countless times.
I think the mistake you’re making is that you’re imagining how locks work. Whereas what I am doing is running rigorous experiments that involved putting WebKit through larger scale tests
You say this with zero data.
I know that yielding 40 times is optimal for WebKit because I measured it. In fact it was re-measured many times because folks like you would doubt that it could’ve optimal, suggest something different, and then again the 40 yields would be shown to be optimal.
> And no if you read the code, they do spin. Worse, they actually yield the thread before properly parking.
Threads wait if the lock is not available immediately-ish.
Yes, they spin by yielding. Spinning by pausing or doing anything else results in worse performance. We measured this countless times.
I think the mistake you’re making is that you’re imagining how locks work. Whereas what I am doing is running rigorous experiments that involved putting WebKit through larger scale tests