On Mon, Jun 5, 2017 at 9:22 AM, Sokolov Yura <funny.fal...@postgrespro.ru> wrote: > Good day, everyone. > > This patch improves performance of contended LWLock. > It was tested on 4 socket 72 core x86 server (144 HT) Centos 7.1 > gcc 4.8.5 > > Patch makes lock acquiring in single CAS loop: > 1. LWLock->state is read, and ability for lock acquiring is detected. > If there is possibility to take a lock, CAS tried. > If CAS were successful, lock is aquired (same to original version). > 2. but if lock is currently held by other backend, we check ability for > taking WaitList lock. If wait list lock is not help by anyone, CAS > perfomed for taking WaitList lock and set LW_FLAG_HAS_WAITERS at once. > If CAS were successful, then LWLock were still held at the moment wait > list lock were held - this proves correctness of new algorithm. And > Proc is queued to wait list then. > 3. Otherwise spin_delay is performed, and loop returns to step 1.
Interesting work. Thanks for posting. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
