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Re: spinlock->pthread_mutex : real world results

From: Nils Goroll <slink(at)schokola(dot)de>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, Merlin Moncure <mmoncure(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: spinlock->pthread_mutex : real world results
Date: 2012-08-06 22:10:02
Message-ID: 502040BA.7010500@schokola.de (view raw or flat)
Thread:
Lists: pgsql-hackers
Robert,

> 1. How much we're paying for this in the uncontended case?

Using glibc, we have the overhead of an additional library function call, which 
we could eliminate by pulling in the code from glibc/nptl or a source of other 
proven reference code.

The pgbench results I had posted before 
http://archives.postgresql.org/pgsql-hackers/2012-07/msg00061.php could give an 
indication on the higher base cost for the simple approach.


I have mentioned this before: While I agree that minimizing the base overhead is 
good, IMHO, optimizing the worst case is the important part here.

Nils

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