From: Bruce Ellis <bruce.ellis@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] userspace semlocks
Date: Sun, 22 Sep 2013 15:48:39 +1000 [thread overview]
Message-ID: <CAJQxxw=KpdBcoC1suKHDsLbCX0mnm-pR+QNS-b11VEM2w-bOcQ@mail.gmail.com> (raw)
In-Reply-To: <64cc61c082febe489ac3244473bb4ca4@brasstown.quanstro.net>
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you are missing the reason. read the paper.
brucee
On 22 September 2013 12:55, erik quanstrom <quanstro@quanstro.net> wrote:
> when i measure chan send performance with the attached program with
> the semaphore locks that have been made the default for sources and
> with the old locks, the old locks surprisingly outperform the new ones
> by a large margin.
>
> the test is let O be the number of buffers in the channel, and M be
> the number of sending procs, then cycles is the number of machine
> cycles required to send 1<<21 messages per proc, and receive them
> on a single listener.
>
> on my machine, i get the following raw numbers (averaged over a few tries):
>
> new 1.84e9 cycles O=10 M=1
> old 1.10e9
>
> new 4.61e9 O=0 M=1
> old 4.38e9
>
> new 1.55e10 O=10 M=8
> old 2.74e10
>
> new 3.64e10 O=0 M=8
> old 5.14e10
>
> am i doing something fundamental wrong, or are the new locks substantially
> slower than the old ones?
>
> - erik
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next prev parent reply other threads:[~2013-09-22 5:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-22 2:55 erik quanstrom
2013-09-22 5:48 ` Bruce Ellis [this message]
2013-09-23 13:56 ` erik quanstrom
2013-09-23 21:11 ` Charles Forsyth
2013-09-23 21:19 ` erik quanstrom
2013-09-23 22:27 ` erik quanstrom
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