Re: sema replacement

[Chuck Tuffli <chuck_tuffli@xxxxxxxxxxx>]

It looks like the code queues up a request and then uses sema_wait() to 
sleep until the request either completes or fails. In both cases, the 
code calls sema_post(). Maybe this is a better fit for messaging - i.e. 
sema_wait would map to lwkt_waitport() and sema_post would map to 
lwkt_sendmsg()?

Matthew Dillon wrote:
> :FreeBSD's new ATA code makes use of kernel counting semaphores (sema(9)) 
> :in the queuing code which don't seem to exist in DragonFly*. I think the 
> :serializing tokens are the replacement and wanted to see if a) that was 
> :the right approach and if so, b) do you use lockmgr or is it preferable 
> :to use the tokens directly. TIA
> :
> :* though, there does seem to be a private implementation in ffs_softdep.c
> :
> :-- 
> :Chuck Tuffli
> :Agilent Technologies
>
>     I would say we want to use tokens for now.  The ATA driver core should
>     be mostly non-blocking, at least presuming that sos hasn't added
>     mallocs in the middle of the code (like existed in the original 4.x
>     driver).  This makes the token model a better fit.
>
>     I won't even ask why they are using yet another (this is like the 
>     8th or 9th now) locking API.  Semaphores don't really fit the model for
>     the type of locking they need.
>
> 					-Matt
> 					Matthew Dillon 
> 					<dillon@xxxxxxxxxxxxx>

--
Chuck Tuffli
Agilent Technologies