Re: Update on the spinlock->pthread_mutex patch experimental: replace s_lock spinlock code with pthread_mutex on linux

From: Merlin Moncure <mmoncure(at)gmail(dot)com>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org, Nils Goroll <slink(at)schokola(dot)de>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Martijn van Oosterhout <kleptog(at)svana(dot)org>
Subject: Re: Update on the spinlock->pthread_mutex patch experimental: replace s_lock spinlock code with pthread_mutex on linux
Date: 2012-06-29 18:24:02
Message-ID: CAHyXU0zV9Hmwmmoq=4oOw5-Mdx1j8xyr+vJrqWPduanRVwxGEA@mail.gmail.com
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On Fri, Jun 29, 2012 at 12:11 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> On Friday, June 29, 2012 07:07:11 PM Nils Goroll wrote:
>> > Also, 20 transactions per connection is not enough of a run to make
>> > any evaluation on.
>>
>> As you can see I've repeated the tests 10 times. I've tested slight
>> variations as mentioned above, so I was looking for quick results with
>> acceptable variation.
> Running only 20 transactions is still meaningless. Quite often that will means
> that no backends run concurrently because the starting up takes longer than to
> process those 20 transactions. You need at the very, very least 10s. Check out
> -T.

yeah. also, standard pgbench is typically very much i/o bound on
typical hardware. it's would be much more interesting to see
performance in spinlock heavy workloads -- the OP noted one when
introducing the thread. would it be possible to simulate those
conditions.

merlin

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