Re: profiling connection overhead

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Tom Lane <tgl@sss.pgh.pa.us>, HeikkiLinnakangas <heikki.linnakangas@enterprisedb.com>
Date: 2010-11-24T21:18:08Z
Lists: pgsql-hackers
On Nov 24, 2010, at 4:05 PM, Andres Freund <andres@anarazel.de> wrote:
>>> 
>>> Won't this just cause loads of additional pagefaults after fork() when
>>> those pages are used the first time and then a second time when first
>>> written to (to copy it)?
>> 
>> Aren't we incurring those page faults anyway, for whatever memory
>> palloc is handing out?  The heap is no different from bss; we just
>> move the pointer with sbrk().
> Yes, but only once. Also scrubbing a page is faster than copying it... (and 
> there were patches floating around to do that in advance, not sure if they got 
> integrated into mainline linux)

I'm not following - can you elaborate?

...Robert