On 04/02/2026 10:02, Bertrand Drouvot wrote:
On Tue, Feb 03, 2026 at 10:29:27PM +0200, Heikki Linnakangas wrote:
There might be a performance argument too,
yeah, not sure but with the patch in place the size of PGPROC goes from
832 bytes to 824 bytes. Is it worth to add extra padding so that it still remain
a multiple of 64?
Hmm, I don't think so. We've never given cacheline alignment any thought
when we've changed the PGPROC fields in the past (or at least I
haven't). Perhaps we should, but it would warrant a separate investigation.
Now that I look at that, the most frequently accessed fields are not at
the beginning or end of the struct, so I don't think there's much harm
in sharing cache lines. And the really hot GetSnapshotData() function
uses the "mirrored" arrays anyway.
- Heikki
