Date: Thu, 13 Oct 2016 18:17:15 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Julien Charbon <jch@freebsd.org> Cc: Konstantin Belousov <kostikbel@gmail.com>, freebsd-stable@FreeBSD.org, hiren panchasara <hiren@strugglingcoder.info> Subject: Re: 11.0 stuck on high network load Message-ID: <20161013151715.GL57714@zxy.spb.ru> In-Reply-To: <33ab0bfc-7009-95a7-7752-c2c439092e85@freebsd.org> References: <20161012095233.GC57714@zxy.spb.ru> <e4f1343c-636a-0970-856b-e65955f79e1a@freebsd.org> <20161012121322.GB57876@zxy.spb.ru> <62d8861c-673e-6d86-e96e-751399e505e5@freebsd.org> <20161012130103.GD57714@zxy.spb.ru> <e8a46471-576d-e074-8a50-5c316fb98bce@freebsd.org> <20161012154229.GC57876@zxy.spb.ru> <bc6810d8-af4c-1716-cbc7-e64819b78ccd@freebsd.org> <20161013143825.GK57714@zxy.spb.ru> <33ab0bfc-7009-95a7-7752-c2c439092e85@freebsd.org>
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On Thu, Oct 13, 2016 at 05:06:00PM +0200, Julien Charbon wrote:
> >> will give you that trace in the core, and without INVARIANT then it is
> >> better to use dtrace:
> >>
> >> $ cat tcp-twstart-dropped.d
> >> fbt::tcp_twstart:entry
> >> /args[0]->t_inpcb->inp_flags & 0x04000000/
> >> {
> >> stack();
> >> printf("INP_DROPPED in tcp_twstart: %x", args[0]->t_inpcb->inp_flags);
> >> }
> >
> > Same code may be insert there too, IMHO.
>
> Hmm, I don't think so:
>
> - If you have INVARIANT, the kernel will panic in tcp_twstart() or
> tcp_detach() and you will have everything you need to debug.
> - If you don't, dtrace is the right tool to use in all cases anyway.
dtrace don't executed in may case w/ diagnostic "dtrace: processing
aborted: Abort due to systemic unresponsiveness". This is for
tcp_close. May be tcp_twstart will be more successuful, may be not.
Also, using dtrace too complex in production (need complex startup
under screen and capture output) and for many peoples.
kdb_backtrace() have too less administrative overhead.
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