On Tue, Dec 10, 2024 at 6:32 PM Andrey M. Borodin <[email protected]> wrote:
>
>
>
> > On 10 Dec 2024, at 15:39, Yura Sokolov <[email protected]> wrote:
> >
> > It is not critical bug, since it doesn't hurt correctness just performance.
> > In worst case only one bank will be used.
>
> Ugh... yeah. IMO the problem is that we do not have protection that rejects
> values that are not power of 2.
> If other values given system operates as if there are 2^(popcount(n)-1)
> banks. So if we just round down value to nearest power of 2 - we will help
> incorrectly configured systems to use proper amount of memory and keep
> performance of properly configured systems.
>
> IMO doing modulo is not necessary. And hash function is pure waste of CPU
> cycles.
IIUC, we do check that it should be in multiple of bank size (i.e.)
which is multiple of 2, right? Am I missing something?
/*
* Helper function for GUC check_hook to check whether slru buffers are in
* multiples of SLRU_BANK_SIZE.
*/
bool
check_slru_buffers(const char *name, int *newval)
{
/* Valid values are multiples of SLRU_BANK_SIZE */
if (*newval % SLRU_BANK_SIZE == 0)
return true;
GUC_check_errdetail("\"%s\" must be a multiple of %d", name,
SLRU_BANK_SIZE);
return false;
}
--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com
