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Date:      Mon, 5 Sep 2016 11:50:28 -0600
From:      Warner Losh <imp@bsdimp.com>
To:        Slawa Olhovchenkov <slw@zxy.spb.ru>
Cc:        hiren panchasara <hiren@strugglingcoder.info>,  FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org>
Subject:   Re: 11.0 stuck on high network load
Message-ID:  <CANCZdfoCHPCmodBxTQysq9DLbppOz2mpNH8rs0N_L1BrpyQv0Q@mail.gmail.com>
In-Reply-To: <20160905164656.GG34394@zxy.spb.ru>
References:  <20160904215739.GC22212@zxy.spb.ru> <20160905014612.GA42393@strugglingcoder.info> <20160905074348.GE34394@zxy.spb.ru> <CANCZdfoOqVGxiytKRhpFgT6N1EbKyP3qqyj2QQzTbUSPzAQW0A@mail.gmail.com> <20160905164656.GG34394@zxy.spb.ru>

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On Mon, Sep 5, 2016 at 10:46 AM, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote:
> On Mon, Sep 05, 2016 at 10:14:59AM -0600, Warner Losh wrote:
>
>> On Mon, Sep 5, 2016 at 1:43 AM, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote:
>> > On Sun, Sep 04, 2016 at 06:46:12PM -0700, hiren panchasara wrote:
>> >
>> >> On 09/05/16 at 12:57P, Slawa Olhovchenkov wrote:
>> >> > I am try using 11.0 on Dual E5-2620 (no X2APIC).
>> >> > Under high network load and may be addtional conditional system go to
>> >> > unresponsible state -- no reaction to network and console (USB IPMI
>> >> > emulation). INVARIANTS give to high overhad. Is this exist some way to
>> >> > debug this?
>> >>
>> >> Can you panic it from console to get to db> to get backtrace and other
>> >> info when it goes unresponsive?
>> >
>> > no
>> > no reaction
>>
>> So the canonical 'ipmitool chassis power diag' doesn't send an NMI to
>> get you to the debugger?
>
> Don't try (and don't know about this).
> Can you some explain?

The BCM sends the NMI to the CPU.

> Is this FreeBSD by default catch NMI and enter to debugger?

Yes.

> How to interoperable with USB stack (I am beware USB keyboard may be locked)?

I've just done serial console, so I'm not sure. I think that it works...

>> I've seen this at Netflix on one variant of our flash offload box with
>> a Intel e5-2697v2 running with the Chelsio driver. We're working
>> around it by having fewer receive threads than CPUs in the system. The
>> only way the boxes would come back was with watchdog. The load was
>> streaming video > ~36Gbps out 4 lagged 10G ports. Console is totally
>> unresponsive as well. This is on our FreeBSD-10 stable based fork.
>> >From my debugging, we go from totally fine as far as I can tell from
>> ps, etc in the moments leading to the hang to being totally wedged. It
>> seems a very sudden-onset condition. Sound at all familiar?
>>
>> Warner
>
> Not sure.
> This is less power box and can be servered only 20Gbit, using Intel
> card (lagg 2x10H). Day ago I am using on this box 10-STABLE w/o such
> issuse. (Not cleancly remember, may be some month ago this box crashed
> by this issuse -- at the that time I am don't have any ideas about crash)

OK.

> May be stuck caused by some poor (too big) memory request from nginx
> (atempt parsing some malformed files). Or frequent nginx core dump
> (from this malformed files).

OK. We're using nginx too, with our modified sendfile.

> 11.0 on two different more power box servered from 40 to 55Gbit w/o stuck.
> But w/o malformed files (t.e. w/o bogus memory request and w/o nginx
> crash). Not sure about correlation.

In our case it seems like a timing issue between too many threads. The
same hardware can handle 1x40G no probem...

Warner



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