| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, HeikkiLinnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Subject: | Re: profiling connection overhead |
| Date: | 2010-11-24 21:18:08 |
| Message-ID: | 55CFD67C-7D8E-44A0-970D-5635CBF6A2BE@gmail.com |
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| Lists: | pgsql-hackers |
On Nov 24, 2010, at 4:05 PM, Andres Freund <andres(at)anarazel(dot)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
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