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Re: [libvirt] [PATCH] Enable tuning of qemu network tap device "sndbuf" size



On 01/13/2011 04:21 PM, Eric Blake wrote:
On 01/12/2011 11:45 PM, Laine Stump wrote:
This is in response to a request in:

    https://bugzilla.redhat.com/show_bug.cgi?id=665293

In short, under heavy load, it's possible for qemu's networking to
lock up due to the tap device's default 1MB sndbuf being
inadequate. adding "sndbuf=0" to the qemu commandline -netdevice
option will alleviate this problem (sndbuf=0 actually sets it to
0xffffffff).

Because we must be able to explicitly specify "0" as a value, the
standard practice of "0 means not specified" won't work here. Instead,
virDomainNetDef also has a sndbuf_specified, which defaults to 0, but
is set to 1 if some value was given.

The sndbuf value is put inside a<tune>  element of each<interface>  in
the domain. The intent is that further tunable settings will also be
placed inside this elemnent.
s/elemnent/element/

Fixed.

Also, as with the vhost patch, I didn't get the html docs updated for
this addition either. I will add both in a single followup patch next
week.
Added to my list of things to remind you about, if you forget :)

Also on my own list.


Oh, we don't have virStrToLong_ul.

Now can be changed to "we *didn't* have virStrToLong_ul" :-) Thanks!

I changed all the sndbuf things to unsigned long, and have also changed sndbuf_specified to a bool in v2.


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