From: Jim C. Nasby <jnasby@pervasive.com>
To: Robert Lor <Robert.Lor@Sun.COM>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Tatsuo Ishii <ishii@sraoss.co.jp>
Cc: pgsql-hackers@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: [HACKERS] Sun Donated a Sun Fire T2000 to the PostgreSQL
Date: Fri, 21 Jul 2006 08:56:53 -0500
Message-ID: <20060721135653.GC83250@pervasive.com> (raw)
In-Reply-To: <44C088C8.9050303@sun.com>
References: <20060617.101521.95879771.t-ishii@sraoss.co.jp>
<10226.1150511655@sss.pgh.pa.us>
<20060617.111838.39487910.t-ishii@sraoss.co.jp>
<20060713.180234.45872055.t-ishii@sraoss.co.jp>
<8669.1153422118@sss.pgh.pa.us>
<44C088C8.9050303@sun.com>
On Fri, Jul 21, 2006 at 12:56:56AM -0700, Robert Lor wrote:
> I ran pgbench and fired up a DTrace script using the lwlock probes we've
> added, and it looks like BufMappingLock is the most contended lock, but
> CheckpointStartLocks are held for longer duration!
Not terribly surprising given that that lock can generate a substantial
amount of IO (though looking at the numbers, you might want to make
bgwriter more aggressive). Also, that's a shared lock, so it won't have
nearly the impact that BufMappingLock does.
> Lock Id Mode Count
> ControlFileLock Exclusive 1
> SubtransControlLock Exclusive 1
> BgWriterCommLock Exclusive 6
> FreeSpaceLock Exclusive 6
> FirstLockMgrLock Exclusive 48
> BufFreelistLock Exclusive 74
> BufMappingLock Exclusive 74
> CLogControlLock Exclusive 184
> XidGenLock Exclusive 184
> CheckpointStartLock Shared 185
> WALWriteLock Exclusive 185
> ProcArrayLock Exclusive 368
> CLogControlLock Shared 552
> SubtransControlLock Shared 1273
> WALInsertLock Exclusive 1476
> XidGenLock Shared 1842
> ProcArrayLock Shared 3160
> SInvalLock Shared 3684
> BufMappingLock Shared 14578
>
> Lock Id Combined Time (ns)
> ControlFileLock 7915
> BgWriterCommLock 43438
> FreeSpaceLock 111139
> BufFreelistLock 448530
> FirstLockMgrLock 2879957
> CLogControlLock 4237750
> SubtransControlLock 6378042
> XidGenLock 9500422
> WALInsertLock 16372040
> SInvalLock 23284554
> ProcArrayLock 32188638
> BufMappingLock 113128512
> WALWriteLock 142391501
> CheckpointStartLock 4171106665
>
>
> Regards,
> -Robert
>
>
>
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--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, Robert.Lor@Sun.COM, tgl@sss.pgh.pa.us, ishii@sraoss.co.jp, pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Sun Donated a Sun Fire T2000 to the PostgreSQL
In-Reply-To: <20060721135653.GC83250@pervasive.com>
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