Re: [PATCH 0/2] qemu: Set noqueue qdisc for TAP devices

On 10/13/20 3:09 PM, Daniel Henrique Barboza wrote: > > > On 10/8/20 3:10 PM, Michal Privoznik wrote: >> See 2/2 for detailed explanation. >> Long story short - we can squeeze more bandwidth from TAP devices we >> create for domains. >> >> Michal Prívozník (2): >>    virnetdev: Introduce virNetDevSetRootQDisc() >>    qemu: Set noqueue qdisc for TAP devices > > > Reviewed-by: Daniel Henrique Barboza <danielhb413(a)gmail.com&gt; > Thanks. Just before I merged these I realized that it will be a good idea to mock virNetDevSetRootQDisc() so that we don't run tc from the test suite. But the diff is really trivial: diff --git i/src/util/virnetdev.h w/src/util/virnetdev.h index 82943b8e08..dfef49938f 100644 --- i/src/util/virnetdev.h +++ w/src/util/virnetdev.h @@ -313,6 +313,7 @@ int virNetDevRunEthernetScript(const char *ifname, const char *script)      G_GNUC_NO_INLINE;  int virNetDevSetRootQDisc(const char *ifname, -                          const char *qdisc); +                          const char *qdisc) +    G_GNUC_NO_INLINE;  G_DEFINE_AUTOPTR_CLEANUP_FUNC(virNetDevRxFilter, virNetDevRxFilterFree); diff --git i/tests/qemuxml2argvmock.c w/tests/qemuxml2argvmock.c index 9bf4357b66..b9322f4f2a 100644 --- i/tests/qemuxml2argvmock.c +++ w/tests/qemuxml2argvmock.c @@ -286,3 +286,11 @@ qemuBuildTPMOpenBackendFDs(const char *tpmdev G_GNUC_UNUSED,      *cancelfd = 1731;      return 0;  } + + +int +virNetDevSetRootQDisc(const char *ifname G_GNUC_UNUSED, +                      const char *qdisc G_GNUC_UNUSED) +{ +    return 0; +} Hopefully, you are okay if I squash this to 2/2.

> > Have you tried it out with older kernels? Reading the bug I understood > that 4.2 and older (2015 kernels) does not have qdisc support and that you > can, for example, test for NETIF_F_LLTX of the ETHTOOL_GFEATURES ioctl to > verify it. > I didn't, but I had this on mind when writing patches and I made the whole thing best effort. Note that qemuDomainInterfaceSetDefaultQDisc() retval is not checked for => if setting noqueue fails (for whatever reason) then worst case scenario an error is printed into logs. > I consider this to be a 'nice to have' that can be added in a follow up > patch though, if applicable. By the way, do we have any documentation about > "the latest Libvirt release will not care about N+ years old kernel/QEMU"? I'm not sure what you mean. This perhaps? https://libvirt.org/platforms.html#linux-freebsd-and-macos

Michal