[dpdk-dev] [RFC] ethdev: make rte flow API thread safe

[Stephen Hemminger]

On Mon, 7 Sep 2020 02:36:48 +0000
Suanming Mou <suanmingm at nvidia.com> wrote:

> Hi,
> 
> Sorry for my late reply due to the vacation.
> 
> > What is the performance impact of this for currently working applications that
> > use a single thread to program flow rules.  You are adding a couple of system
> > calls to what was formerly a totally usermode operation.  
> 

Read the source for glibc and see what pthread_mutex does

> If I understand correctly, in the non-contended single thread case, pthread mutex lock should not go to the kernel space.
> I also wrote a small application with pthread mutex, and strace shows no system call was introduced.
> 
> Another simple testing code below is to check the cycles cost difference in every round between pthread mutex and spin_lock.
> 

Micro benchmarks of locking is hard to see.