Re: [RFC][PATCH 1/2] sched: Extended scheduler time slice

On Wed, 5 Feb 2025 21:08:47 +0000
Prakash Sangappa [off-list ref] wrote:

The new syscall/API proposed was to provide per thread shared mapped 
area(shared structure) that are allocated from memory pages that are pinned. 
So the kernel could access it without the need for a copyin/copyout. 

The idea is that it would be helpful in places where we cannot take a page 
fault in the kernel codepath.

What places do we need to decided this in a critical path? If we follow my
proposal, where we set NEED_RESCHED_LAZY on sched_tick when it interrupts
user space, then it should all work out.

I agree with Peter about not caring about system calls. If you can do a
system call in a critical path, then just use futexes.

The only reason I support system calls is for debugging. That's because I
write into the trace_marker from user space to see if things are working,
and that requires a system call. But once things are working, I'll make it
not work for system calls too.

-- Steve