Original URL: https://www.phoronix.com/scan.php?page=news_item&px=Torvalds-On-Scheduler-Woes
On Wednesday Phoronix cited a blog post by C++ game developer Malte Skarupke claiming his spinlocks experiments had discovered the Linux kernel had a scheduler issue affecting developers bringing games to Linux for Google Stadia.
Linus Torvalds has now responded:
The whole post seems to be just wrong, and is measuring something completely different than what the author thinks and claims it is measuring.
First off, spinlocks can only be used if you actually know you’re not being scheduled while using them. But the blog post author seems to be implementing his own spinlocks in user space with no regard for whether the lock user might be scheduled or not. And the code used for the claimed “lock not held” timing is complete garbage.
It basically reads the time before releasing the lock, and then it reads it after acquiring the lock again, and claims that the time difference is the