Ühel kenal päeval, T, 2007-03-13 kell 12:53, kirjutas Tom Lane:
> Jeff Davis <[EMAIL PROTECTED]> writes:
> > I agree that ss_report_loc() doesn't need to report on every call. If
> > there's any significant overhead I agree that it should report less
> > often. Do you think that the overhead is significant on such a simple
> > function?
> One extra LWLock cycle per page processed definitely *is* a significant
> overhead ... can you say "context swap storm"?  I'd think about doing it
> once every 100 or so pages.

Can't we do it in some lock-free way ? writing page numbers (4-byte
ints) into a predetermined location isn shared mem should be atomic on
all platforms we support (still may cause some cache ping-pong in
multiprocessor systems, but this should be much cheaper), and even an
occasional error in establishing the "scan head" should not be

Hannu Krosing
Database Architect
Skype Technologies OÜ
Akadeemia tee 21 F, Tallinn, 12618, Estonia

Skype me:  callto:hkrosing
Get Skype for free:  http://www.skype.com

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