I wrote: > Awhile back, Chris Marcellino <[EMAIL PROTECTED]> wrote: >> If this is in fact the case, I have a trivial patch to conditionally >> enable SysV semaphores based on the OS release:
> I've tried this patch on my Mac laptop, and while it seems to work as > advertised in terms of not eating a boatload of file descriptors, > I was disturbed to find that it seems consistently a couple percent > slower than the POSIX-sema code according to pgbench. I rechecked this using PG CVS HEAD and can no longer reproduce a slowdown --- in fact, the SYSV-sema code is marginally faster. It's well within the noise level of pgbench, but anyway this seems enough to allay my fears of a performance drop: posix: g42:~ tgl$ pgbench -c 10 -t 1000 bench starting vacuum...end. transaction type: TPC-B (sort of) scaling factor: 10 number of clients: 10 number of transactions per client: 1000 number of transactions actually processed: 10000/10000 tps = 107.051937 (including connections establishing) tps = 107.207220 (excluding connections establishing) sysv: g42:~ tgl$ pgbench -c 10 -t 1000 bench starting vacuum...end. transaction type: TPC-B (sort of) scaling factor: 10 number of clients: 10 number of transactions per client: 1000 number of transactions actually processed: 10000/10000 tps = 107.565526 (including connections establishing) tps = 107.730181 (excluding connections establishing) I am not sure what changed since May, but one possibility is that I just recently boosted the sysv shmem limit on my laptop. I think the previous runs were probably taken with max_connections of 30 or so, whereas these numbers have max_connections = 100. That's relevant since there are 3x more semaphores needed. Anyway, getting rid of all the file descriptors for Posix semas seems Clearly A Good Idea, so I'll go ahead and apply this patch. Thanks for sending it in. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly