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Date: Fri, 19 Feb 2016 14:14:24 -0500
Message-ID: <CAGtEZUCnXDbKb6ZpXbV6Mz=1x=Z6syzUBdvuxRs-3Ch3k5m1sw@mail.gmail.com>
Subject: Re: dtracing ZFS on FreeBSD
From: Tom Curry <thomasrcurry@gmail.com>
To: "Michael W. Lucas" <mwlucas@michaelwlucas.com>
Cc: fs@freebsd.org
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On Fri, Feb 19, 2016 at 2:07 PM, Michael W. Lucas <mwlucas@michaelwlucas.com
> wrote:

> On Fri, Feb 19, 2016 at 01:51:21PM -0500, Tom Curry wrote:
> >    For the variable drops you could try increasing the buffer size, I
> know
> >    I ran into this when I was tracing something very noisy and it
> >    definitely helped.
> >    #pragma D option bufsize=1m
>
> Cranking it up to the limit of 16m helps, thank you.
>
> But the problem still appears during load, just not as often.
>
> Any other suggestions, anyone?
>
>
One other thing to try in concert with the larger buffer,

#pragma D option bufpolicy=ring

In theory I would expect it not to drop, but the window of tracing would be
smaller.