Date: Fri, 11 Dec 2015 19:14:41 +0300
From: Aleksander Alekseev <a.alekseev@postgrespro.ru>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Patch: fix lock contention for HASHHDR.mutex
Message-ID: <20151211191441.3cc507b5@fujitsu>
In-Reply-To: <772.1449847830@sss.pgh.pa.us>
References: <20151211170001.78ded9d7@fujitsu>
	<772.1449847830@sss.pgh.pa.us>
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Hello, Tom

I see your point, but I would like to clarify a few things.

1. Do we consider described measurement method good enough to conclude
that sometimes PostgreSQL really spends 3 ms in a spinlock (like a RTT
between two Internet hosts in the same city)? If not, what method
should be used to approve or disapprove this?

2. If we agree that PostgreSQL does sometimes spend 3 ms in a spinlock
do we consider this a problem?

3. If we consider this a problem, what method is considered appropriate
to find a real reason of such behaviour so we could fix it?

Best regards,
Aleksander


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