[Pvfs2-developers] [PATCH] threaded kmod helper

[Rob Ross]

Fine by me. I agree with Sam that the threaded version probably ought  
to be the default *eventually*, but that it's really low on the list  
of priorities. -- Rob


> On Feb 14, 2008, at 5:18 PM, Sam Lang wrote:
>>
>> On Feb 14, 2008, at 4:34 PM, Pete Wyckoff wrote:
>>>
>>> What does everybody think about this?
>>
>> I think the patch looks great.  My only concern is that this will  
>> make the threaded client daemon never get used.  My view is that we  
>> should probably have the threaded version as the default.  I think  
>> in the general case, the threaded version is going to perform  
>> better.  Its pretty hard to buy a system that doesn't have at least  
>> two cores today, and even on a uni-processor system, the  
>> performance of the threaded daemon shouldn't be much worse than the  
>> non-threaded.
>>
>> I originally added the threaded client functionality to see if it  
>> would help performance, but it turned out to be buggy.  Maybe with  
>> Phil's recent thread-safety fixes to the system interfaces, we  
>> should revisit making the threaded daemon the default.
>>
>> I'm not sure that the overhead of a single operation will be  
>> affected much, honestly.  We can't disable threads and locking  
>> entirely, since we need the remount thread running.  I think the  
>> patch I just committed to fix the segfault in HEAD will likely help  
>> with individual operation performance more than disabling threads  
>> would.  Just my 2c though.
>> Its hard to get a feeling for how much the threaded daemon would  
>> help without a thorough performance analysis of the two on a number  
>> of different systems.  Something I would like to do at some point,  
>> but its pretty low on the list.