[libvirt] [PATCH 4/5] qemu: Add -mem-path even with numa

[John Ferlan]

On 10/01/2015 08:10 AM, Martin Kletzander wrote:
> Of course this will be used only in case we don't need the
> memory-backend-file backend, so it should not fire until later.
> 

So if I'm reading things right... when building the numa string, if it's
determine that "-object" and ",memdev=ram-node%zu" will be required,
then it's also required to have "-mem-alloc -mem-path ..."

(furrowing through the qemu docs was more difficult than I thought)

> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  src/qemu/qemu_command.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 

Perhaps "outside" the domain of these changes; however, I note that the
call to qemuBuildNumaArgStr is from qemuBuildCommandLine as follows:

    if (virDomainNumaGetNodeCount(def->numa)) {
        if (qemuBuildNumaArgStr(cfg, def, cmd, qemuCaps, nodeset) < 0)

one of the first things done in qemuBuildNumaArgStr:

    size_t ncells = virDomainNumaGetNodeCount(def->numa);

oh and of course the pesky

    const long system_page_size = virGetSystemPageSizeKB();

I mentioned previously

BTW: Not noted by Coverity, but interestingly later in the code there's:

        if (ncells) {
            /* Fortunately, we allow only guest NUMA nodes to be continuous
             * starting from zero. */
            pos = ncells - 1;
        }

Which if I'm reading things correct - cannot happen.

Just a note - you don't have to change/fix this, but well if you want to...

ACK to what's here as it seems reasonable - perhaps a better reason in
the commit message would help

John

> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 17e5cfd71702..321a5e931350 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -8132,6 +8132,10 @@ qemuBuildNumaArgStr(virQEMUDriverConfigPtr cfg,
>          }
>      }
> 
> +    if (!needBackend &&
> +        qemuBuildMemPathStr(cfg, def, qemuCaps, cmd) < 0)
> +        goto cleanup;
> +
>      for (i = 0; i < ncells; i++) {
>          VIR_FREE(cpumask);
>          if (!(cpumask = virBitmapFormat(virDomainNumaGetNodeCpumask(def->numa, i))))
>