Re: [dpdk-dev] [PATCH v5 2/2] ethdev: make rte_flow API thread safe

[Thomas Monjalon <thomas@monjalon.net>]

15/10/2020 03:07, Suanming Mou:
> Currently, the rte_flow functions are not defined as thread safe.
> DPDK applications either call the functions in single thread or
> protect any concurrent calling for the rte_flow operations using
> a lock.
> 
> For PMDs support the flow operations thread safe natively, the
> redundant protection in application hurts the performance of the
> rte_flow operation functions.
> 
> And the restriction of thread safe is not guaranteed for the
> rte_flow functions also limits the applications' expectation.
> 
> This feature is going to change the rte_flow functions to be thread
> safe. As different PMDs have different flow operations, some may
> support thread safe already and others may not. For PMDs don't
> support flow thread safe operation, a new lock is defined in ethdev
> in order to protects thread unsafe PMDs from rte_flow level.
> 
> A new RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE device flag is added to
> determine whether the PMD supports thread safe flow operation or not.
> For PMDs support thread safe flow operations, set the
> RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE flag, rte_flow level functions will
> skip the thread safe helper lock for these PMDs. Again the rte_flow
> level thread safe lock only works when PMD operation functions are
> not thread safe.
> 
> For the PMDs which don't want the default mutex lock, just set the
> flag in the PMD, and add the prefer type of lock in the PMD. Then
> the default mutex lock is easily replaced by the PMD level lock.
> 
> The change has no effect on the current DPDK applications. No change
> is required for the current DPDK applications. For the standard posix
> pthread_mutex, if no lock contention with the added rte_flow level
> mutex, the mutex only does the atomic increasing in
> pthread_mutex_lock() and decreasing in
> pthread_mutex_unlock(). No futex() syscall will be involved.
> 
> Signed-off-by: Suanming Mou <suanmingm@nvidia.com>
> Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
> Acked-by: Ori Kam <orika@nvidia.com>
> Acked-by: Matan Azrad <matan@nvidia.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>