| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Robert Haas <robertmhaas(at)gmail(dot)com>, Peter Geoghegan <pg(at)heroku(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clock sweep not caching enough B-Tree leaf pages? |
| Date: | 2014-04-17 19:09:43 |
| Message-ID: | 20593.1397761783@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Stephen Frost <sfrost(at)snowman(dot)net> writes:
> I wonder if it would help to actually tell the OS to read in buffers
> that we're *evicting*... On the general notion that if the OS already
> has them buffered then it's almost a no-op, and if it doesn't and it's
> actually a 'hot' buffer that we're gonna need again shortly, the OS will
> have it.
But if it's actually gone cold, you're just forcing unnecessary read I/O,
not to mention possibly causing something slightly warmer to be lost from
kernel cache.
regards, tom lane
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