Re: tcp_vtw fail (was: Re: CVS commit: src)

[Matthew Mondor <mm_lists%pulsar-zone.net@localhost>]

On Tue, 17 May 2011 08:09:55 +0000
David Holland <dholland-current%netbsd.org@localhost> wrote:

> Yeah, so this turns out to be because the tcp_vtw code unconditionally
> allocates about 9M of memory for vestigial connection entries (or
> some such thing) even when it's AFAICT not in use.

>  int  tcp4_vtw_enable = 0;            /* 1 to enable */
>  int  tcp6_vtw_enable = 0;            /* 1 to enable */
>  int  tcp_vtw_was_enabled = 0;
> -int  tcp_vtw_entries = 1 << 16;      /* 64K vestigial TIME_WAIT entries */
> +int  tcp_vtw_entries = 1 << 4;       /* 16 vestigial TIME_WAIT entries */

Strikes me as odd if they're really being allocated despite the feature
being disabled.

I'm not very familiar with this other than the previous discussions
about it here, but was 64K entries the default because it's
performance-critical?

If so, would it be possible to dynamically resize these, controled by a
sysctl stub (or even better, automatically via heuristics in the long
run)?

Thanks,
-- 
Matt