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Date: Fri, 22 Jul 2011 17:16:18 -0700
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From: Garrett Cooper <yanegomi@gmail.com>
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Subject: Re: What is slowhz?
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On Fri, Jul 22, 2011 at 3:10 PM, Garrett Cooper <yanegomi@gmail.com> wrote:
> =A0 =A0I see this comment, and I've found references to a
> net.inet.tcp.slowhz in Free, Net, and OpenBSDs, but this value can't
> be queried anymore.
>
> # grep -r slowhz /sys/
> /sys/netinet/ip.h:#define =A0 =A0 =A0 IPFRAGTTL =A0 =A0 =A0 60 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0/* time to live for frags, slowhz */
>
> =A0 =A0Could someone please confirm that slowhz is indeed a half second
> value [1], or was it tunable / does it matter anymore?

Answering my own question...

/sys/sys/protosw.h:

...

* every 500ms through the pr_slowtimo for timer based actions.

...

#define PR_SLOWHZ       2               /* 2 slow timeouts per second */

> =A0 =A0For additional context, I'm trying to map IP-MIB::ipReasmTimeout
> to a value used in the FreeBSD networking stack, and it looks like
> that value is the best candidate.

This is of course IP-MIB::ipReasmTimeout =3D IFRAGTTL / PR_SLOWHZ =3D 30 se=
conds.

> 1. http://markmail.org/message/3xvte6uxrhyb4spn

Thanks!
-Garrett