On Mon, 29 Oct 2007, Kris Kennaway wrote:
> Daniel Eischen wrote:
>> On Mon, 29 Oct 2007, Kris Kennaway wrote:
>>
>>> Daniel Eischen wrote:
>>>> On Mon, 29 Oct 2007, Kris Kennaway wrote:
>>>>
>>>>> Daniel Eischen wrote:
>>>>>>
>>>>>> The libkse implementation already spins for a bit. The default
>>>>>> number of spins is 500.
>>>>>
>>>>> OK, cool.
>>>>>
>>>>>> I'm not sure that another mutex type is warranted, the default
>>>>>> mutex implementation should be adaptive I think.
>>>>>
>>>>> The point being that certain existing applications already know about
>>>>> this mutex name and will use it automatically when it exists.
>>>>>
>>>>> I am a bit wary of making this the default type though. The algorithm
>>>>> is a pessimization when the conditions described above are not true.
>>>>
>>>> I agree, and it applies a little to the KSE approach also.
>>>> Spinning is mostly a hack for not being able to tell in
>>>> userland if a thread is swapped in/out or is on another
>>>> CPU. If you solve that problem, then you can make the
>>>> default mutex adaptive.
>>>
>>> Yeah. It looks like Solaris does this. In principle you could do it
>>> cheaply with a shared page, I'm not sure what Solaris does.
>>
>> I think we should add back the thread mailbox for libthr threads.
>> I was in favor of keeping the mailbox for libthr, and this might
>> be a good use for it.
>
> I am not familiar with that code, can you point me to the change that removed
> it?
This was when David revised libthr, so it never really had a
mailbox. libkse has the mailbox, and I would have preferred
keeping a similar interface for libthr (specifying it on
thr_create(2)). You can look at how it works for KSE as an
example.
--
DE