On Fri, Sep 04, 2015 at 02:51:39PM +1000, David Gibson wrote: > The device tree presented to pseries machine type guests includes an > ibm,chip-id property which gives essentially the socket number of each > vcpu core (individual vcpu threads don't get a node in the device > tree). > > To calculate this, it uses a vcpus_per_socket variable computed as > (smp_cpus / #sockets). This is correct for the usual case where > smp_cpus == smp_threads * smp_cores * #sockets. > > However, you can start QEMU with the number of cores and threads > mismatching the total number of vcpus (whether that _should_ be > permitted is a topic for another day). It's a bit hard to say what > the "real" number of vcpus per socket here is, but for most purposes > (smp_threads * smp_cores) will more meaningfully match how QEMU > behaves with respect to socket boundaries. > > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
Gah, sorry, there's a compile error in this. I got sidetracked
between writing and posting and forgot I hadn't fixed it yet.
> ---
> hw/ppc/spapr.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 783763f..dbc295b 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -595,8 +595,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void
> *fdt, int offset,
> uint32_t page_sizes_prop[64];
> size_t page_sizes_prop_size;
> QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
> - unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
> - uint32_t cpus_per_socket = sockets ? (smp_cpus / sockets) : 1;
> + uint32_t vcpus_per_socket = smp_threads * smp_cores;
> uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)};
>
> _FDT((fdt_setprop_cell(fdt, offset, "reg", index)));
> @@ -665,7 +664,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void
> *fdt, int offset,
> }
>
> _FDT((fdt_setprop_cell(fdt, offset, "ibm,chip-id",
> - cs->cpu_index / cpus_per_socket)));
> + cs->cpu_index / vcpus_per_socket)));
>
> _FDT((fdt_setprop(fdt, offset, "ibm,pft-size",
> pft_size_prop, sizeof(pft_size_prop))));
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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