[dpdk-dev] [PATCH v4] pflock: add phase-fair reader writer locks

[Stephen Hemminger]

On Mon, 29 Mar 2021 22:00:47 -0700
Stephen Hemminger <stephen at networkplumber.org> wrote:

> This is a new type of reader-writer lock that provides better fairness
> guarantees which better suited for typical DPDK applications.
> A pflock has two ticket pools, one for readers and one
> for writers.
> 
> Phase fair reader writer locks ensure that neither reader nor writer will be
> starved. Neither reader or writer are preferred, they execute in
> alternating phases. All operations of the same type (reader or writer)
> that acquire the lock are handled in FIFO order.  Write
> operations are exclusive, and multiple read operations can be run
> together (until a write arrives).
> 
> A similar implementation is in Concurrency Kit package in FreeBSD.
> For more information see:
>    "Reader-Writer Synchronization for Shared-Memory Multiprocessor
>     Real-Time Systems",
>     http://www.cs.unc.edu/~anderson/papers/ecrts09b.pdf
> 
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>

v4 incorporates feedback, adds some comments and drops the trylock for now.