Em seg., 4 de mar. de 2024 às 03:18, Andrey M. Borodin <x4mmm@yandex-team.ru> escreveu:
> On 14 Jan 2024, at 18:55, John Naylor <johncnaylorls@gmail.com> wrote: > > On Sat, Jan 13, 2024 at 9:36 PM Ranier Vilela <ranier.vf@gmail.com> wrote: >> >> Em ter., 9 de jan. de 2024 às 06:31, John Naylor <johncnaylorls@gmail.com> escreveu: > >>> This just moves an operation from one place to the other, while >>> obliterating the explanatory comment, so I don't see an advantage. >> >> Well, I think that is precisely the case for using memset. >> The way initialization is currently done is much slower and harmful to the branch. >> Of course, the gain should be small, but it is fully justified for switching to memset. > > We haven't seen any evidence or reasoning for that. Simple > rules-of-thumb are not enough. >
Hi Ranier,
I’ll mark CF entry [0] as “Returned with Feedback”. Feel free to reopen item in this CF or submit to the next, if you want to continue working on this.
I took a glance into the patch, and I would agree that setting field nonzero values with memset() is somewhat unusual. Please provide stronger evidence to do so.
I counted the calls with non-zero memset in the entire postgres code and they are about 183 calls.
I counted the calls with non-zero memset in the entire postgres code and they are about 183 calls.
Does filling a memory area, one by one, with branches, need strong evidence to prove that it is better than filling a memory area, all at once, without branches?
