A wee while ago, USB support on FreeBSD6.2 SMP systems was discouraged. Is that still the case?

[youshi10 at u.washington.edu]

On Wed, 1 Aug 2007, Brett Davidson wrote:

> youshi10 at u.washington.edu wrote:
>> On Wed, 1 Aug 2007, Brett Davidson wrote:
>> 
>>> If there are patches/updates to this issue I would REALLY like to know 
>>> about them! :-)
>>> 
>>> -- 
>>> Brett Davidson
>>> Systems Engineer
>>> -- Net24 Limited
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>> 
>> I may be wrong, but USB support has always been giant-locked, and continues 
>> to be giant-locked, at least until Hans work maybe gets integrated into 
>> 8-CURRENT after a major code review.
>> 
>> -Garrett
>> 
> Thanks Garrett.
>
> By the way, my colleague informed me incorrectly that USB and SMP support was 
> an issue. (Although I am keen for this to work!) :-)

Heh :).

> From the latest source, the Kernel PAE conf file mentions that USB and PAE are 
> not known to play well together. This is my immediate concern.

Not sure if that's a problem. PAE is just an ugly ugly hack, but you probably know that by now... should have gone with amd64 ;).

> I presume giant-locking is one mutex that rules them all? As such, besides 
> being inefficient under load, how would running USB under this be a problem 
> with PAE?

Uhm, it's sorta like that. Many drivers are still using giant-locks, but there's a lot of effort going into removing those giant locks for creating more SMP'goodness :).

> Cheers,
> Brett.