Critical Sections for userland.
Alfred Perlstein
alfred at freebsd.org
Tue Oct 2 19:54:19 PDT 2007
* Daniel Eischen <deischen at freebsd.org> [071002 19:46] wrote:
> On Tue, 2 Oct 2007, Alfred Perlstein wrote:
>
> >Hi guys, we need critical sections for userland here.
> >
> >This is basically to avoid a process being switched out while holding
> >a user level spinlock.
>
> Setting the scheduling class to real-time and using SCHED_FIFO
> and adjusting the thread priority around the lock doesn't work?
Too heavy weight, we want to basically have this sort of code
in userland:
/* assume single threaded process for now */
static int is_critical;
atomic_mutex_lock(); /* implies ++is_critical */
...do stuff...
atomic_mutex_unlock(); /* implies --is_critical */
We don't want two or more syscalls per lock operation. :)
--
- Alfred Perlstein
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