Control: tag -1 + confirmed
On Fri, 17 Sep 2021 22:36:28 +0200 Laurent Bigonville <bi...@debian.org> wrote:
Source: qemu
Version: 1:6.1+dfsg-5
Severity: wishlist
Hello,
Apparently qemu support eBPF to speedup the RSS (Receive Side Scaling)
hash calculation in the virtio-net drive.
It might be intresting to enable this.
It requires libbpf-dev that is only available on linux-architectures
Yes, this is as simple as adding a build-dependency.
However things aren't _that_ simple in reality.
And I don't know yet how to deal with all this.
The thing is that (e)bpf support in qemu source is a bit
interesting.
https://salsa.debian.org/qemu-team/qemu/-/blob/master/ebpf/rss.bpf.skeleton.h#L138
It includes a pre-compiled program which is embedded inside an
generated source file (rss.bpf.skeleton.h).
docs/devel/ebpf_rss.rst outlines steps to build that whole file:
llvm, clang, kernel source tree, bpftool
Adjust Makefile.ebpf to reflect the location of the kernel source tree.
$ cd tools/ebpf
$ make -f Makefile.ebpf
I'm not sure I want to add all that stuff to build-dependencies.
And I don't think it's okay to use the compiled program (it is
essentially an .o file) in the build process.
For now, when (e)bpf support is disabled, this file is not included
into compiled qemu binary, so we are at least TRIES to comply to DFSG.
But after enabling it, the file will be compiled into, and this makes
me really wonder...
I don't really know what to do with this.
/mjt
