Re: Dynamically allocated locks

[jonathan%dsg.stanford.edu@localhost]

In message <FA2A84E8-8919-42A8-883C-A6658DCC3FE6%shagadelic.org@localhost>,
Jason Thorpe writes:

>
>On Mar 24, 2008, at 10:10 AM, Matt Thomas wrote:
>
>> Yes.  One / cacheline size is a dramatic waste of space.  Some  
>> systems have
>> 128 bytes per cacheline.  On systems with small caches or UP systems  
>> it's
>> extremely expensive.
>
>Two independent locks in a single cache line is guaranteed to crease a  
>false-sharing situation.  It is best avoided, even if cache pressure  
>is the trade-off.

Even on a UP system?  In the kernel? Surely not.