Eliminate divide in new fast-path locking code c4d5cb71d2 adjusted the fast-path locking code to allow some configuration of the number of fast-path locking slots via the max_locks_per_transaction GUC. In that commit the FAST_PATH_REL_GROUP() macro used integer division to determine the fast-path locking group slot to use for the lock.
The divisor in this case is always a power-of-two value. Here we swap out the divide by a bitwise-AND, which is a significantly faster operation to perform. In passing, adjust the code that's setting FastPathLockGroupsPerBackend so that it's more clear that the value being set is a power-of-two. Also, adjust some comments in the area which contained some magic numbers. It seems better to justify the 1024 upper limit in the location where the #define is made instead of where it is used. Author: David Rowley <drowle...@gmail.com> Reviewed-by: Tomas Vondra <to...@vondra.me> Discussion: https://postgr.es/m/CAApHDvodr3bcnpxcs7+k-3cFwYR0tP-BYhyd2PpDhe-bCx9i=g...@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/936457419d797dfaf37191db53d5efb1279eae6d Modified Files -------------- src/backend/storage/lmgr/lock.c | 5 ++++- src/backend/utils/init/postinit.c | 34 +++++++++++++++------------------- src/include/storage/proc.h | 8 ++++++++ 3 files changed, 27 insertions(+), 20 deletions(-)
