Message ID | 1441342300-28318-2-git-send-email-david@gibson.dropbear.id.au |
---|---|
State | New |
Headers | show |
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 <david@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))));
On 09/04/2015 02:56 PM, David Gibson wrote: > 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 <david@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. The error, I believe, is "opts" not being used anymore? If so, Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> > >> --- >> 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)))); >
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))));
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 <david@gibson.dropbear.id.au> --- hw/ppc/spapr.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)