On Fri, Jul 02, 2021 at 06:07:37PM +0800, Yanan Wang wrote:
> We are currently using maxcpus to calculate value of sockets but using
> cpus to calculate value of cores/threads. This makes cmdlines like
> "-smp 8,maxcpus=12,cores=4" work while "-smp 8,maxcpus=12,sockets=3"
> break the invalid cpu topology check.
>
> This patch allows us to uniformly use maxcpus to calculate the missing
> values. Also the if branch of "cpus == 0 || sockets == 0" was splited
> into branches of "cpus == 0" and "sockets == 0" so that we can clearly
> figure out that we are parsing -smp cmdlines with a preference of cpus
> over sockets over cores over threads.
>
> Signed-off-by: Yanan Wang <wangyana...@huawei.com>
> ---
> hw/core/machine.c | 36 +++++++++++++++++++-----------------
> hw/i386/pc.c | 37 +++++++++++++++++++------------------
> 2 files changed, 38 insertions(+), 35 deletions(-)
>
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 1e194677cd..58882835be 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -752,34 +752,36 @@ static void smp_parse(MachineState *ms,
> SMPConfiguration *config, Error **errp)
> }
>
> /* compute missing values, prefer sockets over cores over threads */
> - if (cpus == 0 || sockets == 0) {
> + maxcpus = maxcpus > 0 ? maxcpus : cpus;
> +
> + if (cpus == 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 {
> - maxcpus = maxcpus > 0 ? maxcpus : cpus;
> - sockets = maxcpus / (cores * threads);
> - sockets = sockets > 0 ? sockets : 1;
> - }
> + cpus = sockets * cores * threads;
> + maxcpus = maxcpus > 0 ? maxcpus : cpus;
> + } else if (sockets == 0) {
> + cores = cores > 0 ? cores : 1;
> + threads = threads > 0 ? threads : 1;
> + sockets = maxcpus / (cores * threads);
> + sockets = sockets > 0 ? sockets : 1;
As stated in the other patch, this rounding up of a fractional sockets
shouldn't be here. maxcpus or (cpus==maxcpus) should always be selected by
the user to be a product of whole number sockets, cores, threads.
> } else if (cores == 0) {
> threads = threads > 0 ? threads : 1;
> - cores = cpus / (sockets * threads);
> + cores = maxcpus / (sockets * threads);
> cores = cores > 0 ? cores : 1;
Now that we're using maxcpus for the calculation, then no rounding for
cores either...
> } else if (threads == 0) {
> - threads = cpus / (cores * sockets);
> + threads = maxcpus / (sockets * cores);
> threads = threads > 0 ? threads : 1;
...or threads.
> - } else if (sockets * cores * threads < cpus) {
> + }
> +
> + if (sockets * cores * threads < cpus) {
> error_setg(errp, "cpu topology: "
> - "sockets (%u) * cores (%u) * threads (%u) < "
> - "smp_cpus (%u)",
> + "sockets (%u) * cores (%u) * threads (%u) "
> + "< smp_cpus (%u)",
Why make this change?
> sockets, cores, threads, cpus);
> return;
> }
>
> - maxcpus = maxcpus > 0 ? maxcpus : cpus;
> -
> if (maxcpus < cpus) {
> error_setg(errp, "maxcpus must be equal to or greater than smp");
> return;
> @@ -795,9 +797,9 @@ static void smp_parse(MachineState *ms, SMPConfiguration
> *config, Error **errp)
> }
>
> ms->smp.cpus = cpus;
> + ms->smp.sockets = sockets;
> ms->smp.cores = cores;
> ms->smp.threads = threads;
> - ms->smp.sockets = sockets;
> ms->smp.max_cpus = maxcpus;
> }
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 93d1f12a49..1812f33ab1 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -721,35 +721,36 @@ static void pc_smp_parse(MachineState *ms,
> SMPConfiguration *config, Error **err
>
> /* compute missing values, prefer sockets over cores over threads */
> dies = dies > 0 ? dies : 1;
> + maxcpus = maxcpus > 0 ? maxcpus : cpus;
>
> - if (cpus == 0 || sockets == 0) {
> + if (cpus == 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 * dies * sockets;
> - } else {
> - maxcpus = maxcpus > 0 ? maxcpus : cpus;
> - sockets = maxcpus / (dies * cores * threads);
> - sockets = sockets > 0 ? sockets : 1;
> - }
> + cpus = sockets * dies * cores * threads;
> + maxcpus = maxcpus > 0 ? maxcpus : cpus;
> + } else if (sockets == 0) {
> + cores = cores > 0 ? cores : 1;
> + threads = threads > 0 ? threads : 1;
> + sockets = maxcpus / (dies * cores * threads);
> + sockets = sockets > 0 ? sockets : 1;
> } else if (cores == 0) {
> threads = threads > 0 ? threads : 1;
> - cores = cpus / (sockets * dies * threads);
> + cores = maxcpus / (sockets * dies * threads);
> cores = cores > 0 ? cores : 1;
> } else if (threads == 0) {
> - threads = cpus / (cores * dies * sockets);
> + threads = maxcpus / (sockets * dies * cores);
> threads = threads > 0 ? threads : 1;
> - } else if (sockets * dies * cores * threads < cpus) {
> + }
> +
> + if (sockets * dies * cores * threads < cpus) {
> error_setg(errp, "cpu topology: "
> - "sockets (%u) * dies (%u) * cores (%u) * threads (%u) < "
> - "smp_cpus (%u)",
> + "sockets (%u) * dies (%u) * cores (%u) * threads (%u) "
> + "< smp_cpus (%u)",
> sockets, dies, cores, threads, cpus);
> return;
> }
>
Same comments as for the general function.
Thanks,
drew
> - maxcpus = maxcpus > 0 ? maxcpus : cpus;
> -
> if (maxcpus < cpus) {
> error_setg(errp, "maxcpus must be equal to or greater than smp");
> return;
> @@ -765,10 +766,10 @@ static void pc_smp_parse(MachineState *ms,
> SMPConfiguration *config, Error **err
> }
>
> ms->smp.cpus = cpus;
> - ms->smp.cores = cores;
> - ms->smp.threads = threads;
> ms->smp.sockets = sockets;
> ms->smp.dies = dies;
> + ms->smp.cores = cores;
> + ms->smp.threads = threads;
> ms->smp.max_cpus = maxcpus;
> }
>
> --
> 2.19.1
>
