On Wed, Aug 29, 2018 at 04:32:01PM +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 <imamm...@redhat.com>
> ---
> 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);
We already have a "max_cpus = qemu_opt_get_number(...)" line in
this function[1]:
/* 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) {
cpus = cores * threads * sockets;
}
} else if (cores == 0) {
[...]
} else if (threads == 0) {
[...]
} else if (sockets * cores * threads < cpus) {
[...]
}
max_cpus = qemu_opt_get_number(opts, "maxcpus", cpus); /* [1] */
/* [2] */
if (max_cpus < cpus) {
error_report("maxcpus must be equal to or greater than smp");
exit(1);
}
Why not move the sockets == 0 check to [2]?
> + sockets = !sockets ? max_cpus / (cores * threads) : sockets;
The two patches in this thread make QEMU print a warning on a
case that was never documented as invalid/deprecated: maxcpus now
needs to be a multiple of cores*threads.
However, the error message doesn't make it obvious:
$ ./x86_64-softmmu/qemu-system-x86_64 -smp 7,cores=3
qemu-system-x86_64: warning: Invalid CPU topology deprecated: sockets (2) *
cores (3) * threads (1) != maxcpus (7)
I think this would make more sense:
$ ./x86_64-softmmu/qemu-system-x86_64 -smp 7,cores=3
qemu-system-x86_64: warning: Invalid CPU topology deprecated: maxcpus (7) is
not a multiple of cores (3) * threads (1)
> }
> } else if (cores == 0) {
> threads = threads > 0 ? threads : 1;
> --
> 2.7.4
>
--
Eduardo
