Re: test branch of patches that use a "tc" filter to fixup UDP checksums
On 11/22/24 11:00 AM, Andrea Bolognani wrote:
On Fri, Nov 22, 2024 at 03:28:00AM -0500, Laine Stump wrote:
> This branch uses tc to fixup the checksum. It's appearing to work with the
> few guests I've tested so far, but there is an issue when a network has
> <bandwidth> configured, and I don't want to post the patches for review
> until I figure that out. In the meantime anyone who wants to test with a
> non-<bandwidth> network, please do :-)
>
> https://gitlab.com/lainestump/libvirt/-/tree/network-freebsd-checksum-fix...
I've tested this with a pretty large variety of guest operating
systems, including the ones that had proven to be incompatible with
the previously attempted solution (GNU/Hurd, Haiku, NetBSD) and those
that are not working correctly today (FreeBSD). Everything seems to
be working fine.
Thanks for the testing - that's very reassuring!
I've never used the <bandwidth> feature so I can't comment on that.
Is it something that is already broken in master, or do these patches
regress that functionality?
I actually didn't test it in master, but assume that it was working.
Both <bandwidth> and the tc-based checksum fix use the same tc "qdisc"
(queue discipline) object to attach their filters, so I've put the
command that adds the qdisc into a separate function that 1) checks if
there's already a qdisc on the interface, and 2) if not it adds one
(using the same code as bandwidth previously used).
Unfortunately the bandwidth code fails to add its filter if the qdisc
had been added by the checksum fix code. I need to grab the exact
commandlines out of the util.command debug log and try reproducing the
issue by hand - hopefully it can be solved by some small change to the
exact commands that are used.
I do think that the structure of the code is sound though, and it can
all be solved by just modifying a commandline argument or two, so it
would be totally reasonable to go over the code to look for obvious
ugliness at least :-)