[haiku-appserver] Re: BScreen support

  • From: Ingo Weinhold <bonefish@xxxxxxxxxxxxxxx>
  • To: haiku-appserver@xxxxxxxxxxxxx
  • Date: Wed, 4 May 2005 16:15:02 +0200 (MEST)

On Wed, 4 May 2005, Stefano Ceccherini wrote:

>>      All commands that affect the visible regions must be >executed from 
>> RootLayer's
>> thread context. When rebuilding regions, again, that must be >done from 
>> RootLayer's thread
>> context. The solution: redirect this message to RT thread >and add a handler 
>> for it.
>>      Locking RootLayer is not a solution, that must be >kept to a minimum (2 
>> such
>> situations ATM).
> Well, if performance is what matters to you, I don't think that locking 
> RootLayer in a display_mode change can affect performance in any way. If 
> there is another reason, please elaborate more on this :)

I also don't quite understand why there should be a performance-wise 
difference between serialization by locking and serialization by 
processing by a single thread in principle. The only thing I see is the 
additional overhead imposed by the messaging mechanism in the latter case.

Generally using a benaphore locking is quite cheap, if the relative time 
the lock is being held is small, since then the locking operations are 
often merely atomic_add()s.

CU, Ingo

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