Re: pgsql: Reduce branches in heapgetpage()'s per-tuple loop
Hi, On 2024-04-07 09:14:57 -0400, Melanie Plageman wrote: > On Sun, Apr 7, 2024 at 3:29 AM Andres Freund wrote: > > > > Reduce branches in heapgetpage()'s per-tuple loop > > > > Until now, heapgetpage()'s loop over all tuples performed some conditional > > checks for each tuple, even though condition did not change across the loop. > > I haven't reviewed exactly what this does, but heapgetpage() was > removed (or split into two functions, rather) in 44086b097537, so I > find the naming of this function, or, at least the comments, commit > message and description a bit confusing. Oops. That name was so ingrained in my head that despite looking over these lines quite a few times, I couldn't spot that. Will send an update to the thread. Greetings, Andres Freund
Re: pgsql: Reduce branches in heapgetpage()'s per-tuple loop
On Sun, Apr 7, 2024 at 3:29 AM Andres Freund wrote: > > Reduce branches in heapgetpage()'s per-tuple loop > > Until now, heapgetpage()'s loop over all tuples performed some conditional > checks for each tuple, even though condition did not change across the loop. I haven't reviewed exactly what this does, but heapgetpage() was removed (or split into two functions, rather) in 44086b097537, so I find the naming of this function, or, at least the comments, commit message and description a bit confusing. - Melanie
pgsql: Reduce branches in heapgetpage()'s per-tuple loop
Reduce branches in heapgetpage()'s per-tuple loop Until now, heapgetpage()'s loop over all tuples performed some conditional checks for each tuple, even though condition did not change across the loop. This commit fixes that by moving the loop into an inline function. By calling it with different constant arguments, the compiler can generate an optimized loop for the different conditions, at the price of two per-page checks. For cases of all-visible tables and an isolation level other than serializable, speedups of up to 25% have been measured. Reviewed-by: John Naylor Reviewed-by: Zhang Mingli Tested-by: Quan Zongliang Discussion: https://postgr.es/m/20230716015656.xjvemfbp5fysj...@awork3.anarazel.de Discussion: https://postgr.es/m/2ef7ff1b-3d18-2283-61b1-bbd25fc6c...@yeah.net Branch -- master Details --- https://git.postgresql.org/pg/commitdiff/a97bbe1f1df9eba0b18207c321c67de80b33db16 Modified Files -- src/backend/access/heap/heapam.c | 102 --- 1 file changed, 74 insertions(+), 28 deletions(-)
