The search for the correct amount of split-lock misery [LWN.net]

The search for the correct amount of split-lock misery

Posted Oct 23, 2022 1:11 UTC (Sun) by NYKevin (subscriber, #129325)
In reply to: The search for the correct amount of split-lock misery by WolfWings
Parent article: The search for the correct amount of split-lock misery

It's not a DDoS, it's just a regular DoS. There's only one system involved.

More to the point, this whole idea is clownshoes anyway. The purpose of the kernel is to serve userspace, not to tell userspace what to do. If userspace wants to hurt its own performance, that's the sysadmin's* problem. For some configurations, it might make sense to allow the sysadmin to block or restrict split-lock operations, but it should function like an rlimit, not a system-wide "block first, ask questions later" flag.

* If there is no sysadmin, that means it's a single-user system and the "problem" is even more nonsensical.

to post comments

The search for the correct amount of split-lock misery

Posted Oct 23, 2022 17:27 UTC (Sun) by marcH (subscriber, #57642) [Link]

> The purpose of the kernel is to serve userspace, not to tell userspace what to do.

No, the purpose of the kernel is to protect userspace from each other (some single application systems don't even have a kernel)

> If userspace wants to hurt its own performance, that's the sysadmin's* problem.

Default settings matter A LOT and it's really good to see overbusy maintainers spending so much time discussing and getting them right.

> > Affected gamers will have to set the new knob appropriately, but knowing which sysctls to tweak could be said to be part of being a true God of War.

Happy ending:
- The "bug" will not go unnoticed and new applications will avoid it
- Old applications will run too after a few minutes searching the Internet.

Very delicate trade-off perfectly found.