| From: | Leonardo Francalanci <m_lists(at)yahoo(dot)it> |
|---|---|
| To: | "sthomas(at)peak6(dot)com" <sthomas(at)peak6(dot)com>, alexandre - aldeia digital <adaldeia(at)gmail(dot)com> |
| Cc: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Adding more memory = hugh cpu load |
| Date: | 2011-10-10 15:14:35 |
| Message-ID: | 1318259675.10344.YahooMailNeo@web29011.mail.ird.yahoo.com |
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| Thread: | |
| Lists: | pgsql-performance |
> That's not entirely surprising. The problem with having lots of memory is...
> that you have lots of memory. The operating system likes to cache, and this
> includes writes. Normally this isn't a problem, but with 48GB of RAM, the
> defaults (for CentOS 5.5 in particular) are to use up to 40% of that to cache
> writes.
I don't understand: don't you want postgresql to issue the fsync calls when
it "makes sense" (and configure them), rather than having the OS decide
when it's best to flush to disk? That is: don't you want all the memory to
be used for caching, unless postgresql says otherwise (calling fsync), instead
of "as soon as 1% of memory is used"?
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