Hi Alicja, Thanks for your advice, now postgresql works fine with 'huge_pages=on'. Regards Bogdan
śr., 7 maj 2025 o 14:17 Alicja Kucharczyk <zaledwie10mi...@gmail.com> napisał(a): > Hi Bogdan, > The root cause here is that the number of huge pages you've configured > (vm.nr_hugepages = 980) is not sufficient. > Each huge page on your system is 2 MB in size, so 980 pages give you > roughly 1.96 GB of memory (980 × 2 MB). However, PostgreSQL is clearly > requesting about 2.2 GB of shared memory (specifically, 2204106752 bytes as > shown in the error message you provided), which exceeds what's available > through huge pages. > > That’s why PostgreSQL fails to start when huge_pages = on - it requires > the entire shared memory segment to come from huge pages and refuses to > fall back to regular ones. > > Earlier, you had the huge_pages setting commented out, which means > PostgreSQL used the default value: huge_pages = try. In that mode, it first > attempts to use huge pages, but if that fails (like in your case due to > insufficient allocation), it falls back to standard memory pages — which is > why the instance started without issues then. > > To fix the issue, you should increase vm.nr_hugepages to at least 1100 to > fully cover the shared memory request (you can go a bit higher to be safe > and then reduce it as described in the article I'm pasting the link to). > > Also, a side note: max_connections = 1000 is quite high for an instance > with 8 GB of RAM and only 2 vCPUs. Even if huge pages are properly > allocated, such a high number of connections can lead to performance > issues. You might want to consider lowering it or using a connection pooler > like PgBouncer. > > If you’d like to understand how huge pages work in PostgreSQL, including > how to calculate memory needs and configure the OS properly, I wrote a > detailed article some time ago (still valid). It’s in Polish, which I > assume is fine for you: > https://linuxpolska.com/pl/baza-wiedzy/blog/postgres-pamieci-ram-tipstricks/ > > best regards, > Alicja Kucharczyk > >>
