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Re: Python 2 and test/vm/netbsd


From: Philippe Mathieu-Daudé
Subject: Re: Python 2 and test/vm/netbsd
Date: Fri, 18 Oct 2019 16:58:00 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1

On 10/18/19 4:29 PM, Eduardo Habkost wrote:
On Fri, Oct 18, 2019 at 12:44:39PM +0200, Gerd Hoffmann wrote:
   Hi,

Running with V=1, I see packages being downloaded at reasonable speeds, but
there's a huge interval (of various minutes) between each package download.

I've found the cause for the slowness I'm seeing: for each file
being downloaded, the guest spents at least 75 seconds trying to
connect to the IPv6 address of ftp.NetBSD.org, before trying
IPv4.

Ah, that nicely explains why it worked just fine for me.  First, I have
a local proxy configured so the installer isn't going to connect to
ftp.NetBSD.org directly.  Second I have IPv6 connectivity.

I don't know if this is a NetBSD bug, or a slirp bug.

Both I'd say ...

First, by default slirp should not send IPv6 router announcements
to the user network if the host has no IPv6 connectivity.

Second, the recommended way to connect is to try ipv4 and ipv6 in
parallel, then use whatever connects first.  Web browsers typically
do it that way.  wget and curl don't do that though, they try one
address after the other, and I guess this is where the delay comes
from ...

In addition to that, the connect() error should be generating a
ICMP6_UNREACH message, and I'd expect the NetBSD guest to notice
it instead of waiting for timeout.

Is this missing in SLiRP?



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