| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Lonni J Friedman <netllama(at)gmail(dot)com> |
| Cc: | Andy Colson <andy(at)squeakycode(dot)net>, pgsql-general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Re: significant performance hit whenever autovacuum runs after upgrading from 9.0 -> 9.1 |
| Date: | 2012-05-23 16:37:54 |
| Message-ID: | 6087.1337791074@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Lonni J Friedman <netllama(at)gmail(dot)com> writes:
> After banging my head on the wall for a long time, I happened to
> notice that khugepaged was consuming 100% CPU every time autovacuum
> was running. I did:
> echo "madvise" > /sys/kernel/mm/transparent_hugepage/defrag
> and immediately the entire problem went away.
Fascinating.
> So this looks like a nasty Fedora16 kernel bug to me, or maybe
> postgresql & Fedora16's default kernel settings are just not
> compatible?
I agree, kernel bug. What kernel version are you using exactly?
> Is anyone else using Fedora16 & PostgreSQL-9.1 ?
I use an F16 box daily, but can't claim to have done major performance
testing with it. Can you put together a summary of your nondefault
Postgres settings? I wonder whether it only kicks in for a certain
size of shared memory for instance.
regards, tom lane
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