> On Mar 31, 2019, at 3:12 PM, Mindaugas Rasiukevicius wrote:
>
> A few comments:
>
> - Kernel preemption is implicitly disabled at IPL_HIGH, so you do not need
> to do it explicitly.
Ah, of course. Makes sense.
> - Consider re-using the cpu_lock instead of adding ucas_critical_mutex.
Don
Jason Thorpe wrote:
> <...>
>
> a) acquire the ucas_critical_mutex.
> b) disable preemption.
> c) go to splhigh().
> d) set ucas_critical_owning_cpu to curcpu().
> e) membar_enter()
> f) Trigger an IPI on all-but-owning-cpu to enter the ucas_critical_gate.
> g) wait for all-but-owning cpu to ente
> On Mar 29, 2019, at 6:16 PM, Jason Thorpe wrote:
>
> Thanks for the pointer -- I'll take a look. The splhigh() should not be a
> problem because the page will be wired.
>
> So, something like:
>
> -- Broadcast IPI
> -- Wait for semaphore variable to reach (ncpuonline - 1)
>
(Apologies for the small-screen reply... picking up someone at the airport, and
this is the device I have handy whilst I wait...)
Yes, sparc and vax have “test-and-set” atomic primitives. Those are perfectly
fine for implementing an interlock in a mutex, but the algorithm I’m
implementing at a
> I'm trying to wrap up my ufetch / ustore changes (http://mail-index.netbsd.o$
> [...]
> Then there are platforms where [ucas is] just missing (sparc, vax).
> These platfo$
Why insist that LL/SC and CAS are the only acceptable primitives, and
that platforms that don't have them in hardware have t
> On Mar 29, 2019, at 3:01 PM, Mindaugas Rasiukevicius wrote:
> I think I might have introduced the ucas_*() API with x86 support back
> in 2009 (and portmasters added it to others architectures, but not all)..
> The ustore/ufetch API was supposed to be a follow-up clean up. Thanks
> for fina
Jason Thorpe wrote:
> Folks...
>
> I'm trying to wrap up my ufetch / ustore changes
> (http://mail-index.netbsd.org/tech-kern/2019/02/23/msg024690.html), and I
> realized there's another requirement that the project I'm working on
> has... specifically, ucas_int() ... for those unfamiliar, this i
Folks...
I'm trying to wrap up my ufetch / ustore changes
(http://mail-index.netbsd.org/tech-kern/2019/02/23/msg024690.html), and I
realized there's another requirement that the project I'm working on has...
specifically, ucas_int() ... for those unfamiliar, this is like
atomic_cas_int(), but
