Re: [libvirt] [Qemu-devel] [PATCH v5 2/2] vl:c: make sure that sockets are calculated correctly in '-smp X' case

On Tue, Sep 04, 2018 at 05:18:48PM +0200, Andrew Jones wrote: > On Tue, Sep 04, 2018 at 03:22:36PM +0200, Igor Mammedov wrote: > > commit > > (5cdc9b76e3 vl.c: Remove dead assignment) > > removed sockets calculation when 'sockets' weren't provided on CLI > > since there wasn't any users for it back then. Exiting checks > > are neither reachable > > } else if (sockets * cores * threads < cpus) { > > or nor triggable > > if (sockets * cores * threads > max_cpus) > > so we weren't noticing wrong topology since then, since users > > recalculate sockets adhoc on their own. > > > > However with deprecation check it becomes noticable, for example > > -smp 2 > > will start printing warning: > > "warning: Invalid CPU topology deprecated: sockets (1) * cores (1) * threads (1) != maxcpus (2)" > > calculating sockets if they weren't specified. > > > > Fix it by returning back sockets calculation if it's omited on CLI. > > > > Signed-off-by: Igor Mammedov <imammedo(a)redhat.com&gt; > > --- > > vl.c | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/vl.c b/vl.c > > index 7fd700e..333d638 100644 > > --- a/vl.c > > +++ b/vl.c > > @@ -1210,11 +1210,14 @@ static void smp_parse(QemuOpts *opts) > > > > /* compute missing values, prefer sockets over cores over threads */ > > if (cpus == 0 || sockets == 0) { > > - sockets = sockets > 0 ? sockets : 1; > > cores = cores > 0 ? cores : 1; > > threads = threads > 0 ? threads : 1; > > if (cpus == 0) { > > + sockets = sockets > 0 ? sockets : 1; > > cpus = cores * threads * sockets; > > + } else { > > + max_cpus = qemu_opt_get_number(opts, "maxcpus", cpus); > > + sockets = !sockets ? max_cpus / (cores * threads) : sockets; Why the !sockets check here? If we have reached this statement we know that (cpus == 0 || sockets == 0) is true and (cpus == 0) is false, so sockets is guaranteed to be 0.

Sorry for not spotting this earlier. > > } > > } else if (cores == 0) { > > threads = threads > 0 ? threads : 1; > > -- > > 2.7.4 > > > > > > Reviewed-by: Andrew Jones <drjones(a)redhat.com&gt;