From: Charles Forsyth <charles.forsyth@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] fossil+venti performance question
Date: Tue, 5 May 2015 23:23:31 +0100 [thread overview]
Message-ID: <CAOw7k5jBr37Owp1_pvjK4GqLCg-rP7Qut8hDci8ZwZ8nr1O1tw@mail.gmail.com> (raw)
In-Reply-To: <CANUoZoGXm6bf_Mi_QNJSmHN6U0yb+3CeVcK_r-UA+PFfDE_NQQ@mail.gmail.com>
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On 5 May 2015 at 16:38, David du Colombier <0intro@gmail.com> wrote:
> > How many times do you time it on each machine?
>
> Maybe ten times. The results are always the same ~5%.
> Also, I restarted vacfs between each try.
It was the effect of the ram caches that prompted the question.
My experience is similar to Steve's: it was faster, and now it's initially
very very slow.
I looked at changes from that version of venti to this, and I didn't see
anything that would cause that.
(The problem could be outside venti, but I looked at some possibly relevant
kernel changes too.)
Note that the raw drive speed on my venti machine is fine (no doubt it
could be better, but it's fine).
I convinced myself through experiments that the problem was with venti, not
fossil.
I used some debugging code in venti and had the impression that it took a
surprisingly long time
to handle each request: that the time was in venti. The effect was similar
to that of a lost
interrupt for a device driver. I used ratrace on it, but didn't spot an
obvious culprit.
I was tempted to rip out or disable the drive scheduling code in venti to
see what happened, but
not for the first time I ran out of time and had to get back to some other
work.
One thing I didn't know was that the results were different when fossil was
on a different machine.
I thought I'd tried that with vacfs myself, but apparently not or mine was
as slow as when on the same
machine.
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next prev parent reply other threads:[~2015-05-05 22:23 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-04 9:32 KADOTA Kyohei
2015-05-04 16:10 ` Anthony Sorace
2015-05-04 18:11 ` Aram Hăvărneanu
2015-05-04 18:51 ` David du Colombier
2015-05-05 14:29 ` Sergey Zhilkin
2015-05-05 15:05 ` Charles Forsyth
2015-05-05 15:38 ` David du Colombier
2015-05-05 22:23 ` Charles Forsyth [this message]
2015-05-05 22:29 ` cinap_lenrek
2015-05-05 22:33 ` David du Colombier
2015-05-05 22:53 ` Aram Hăvărneanu
2015-05-06 20:55 ` David du Colombier
2015-05-06 21:17 ` Charles Forsyth
2015-05-06 21:26 ` David du Colombier
2015-05-06 21:28 ` David du Colombier
2015-05-06 22:28 ` Charles Forsyth
2015-05-07 3:35 ` erik quanstrom
2015-05-07 6:15 ` David du Colombier
2015-05-07 13:17 ` erik quanstrom
2015-05-08 16:13 ` David du Colombier
2015-05-08 16:39 ` Charles Forsyth
2015-05-08 17:16 ` David du Colombier
2015-05-08 19:24 ` David du Colombier
2015-05-08 20:03 ` Steve Simon
2015-05-08 21:19 ` Bakul Shah
2015-05-09 14:43 ` erik quanstrom
2015-05-09 17:25 ` Lyndon Nerenberg
2015-05-09 17:30 ` Devon H. O'Dell
2015-05-09 17:35 ` Lyndon Nerenberg
2015-05-09 21:54 ` Devon H. O'Dell
2015-05-09 18:20 ` Bakul Shah
2015-05-09 3:11 ` cinap_lenrek
2015-05-09 5:59 ` lucio
2015-05-09 16:26 ` cinap_lenrek
2015-05-09 16:23 ` erik quanstrom
2015-05-10 4:55 ` erik quanstrom
2015-05-10 5:07 ` erik quanstrom
2015-05-10 17:57 ` David du Colombier
2015-05-10 20:18 ` erik quanstrom
2015-05-10 20:19 ` cinap_lenrek
2015-05-10 20:51 ` erik quanstrom
2015-05-10 21:34 ` cinap_lenrek
2015-05-11 1:23 ` erik quanstrom
2015-05-09 16:59 ` erik quanstrom
2015-05-06 22:35 ` Steven Stallion
2015-05-06 23:47 ` Charles Forsyth
2015-05-07 3:38 ` erik quanstrom
2015-05-07 3:43 ` erik quanstrom
2015-05-05 15:07 ` KADOTA Kyohei
2015-05-05 14:47 ` KADOTA Kyohei
2015-05-05 15:46 ` steve
2015-05-05 15:54 ` David du Colombier
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