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[Qemu-ppc] [PATCH RFC] spapr: disintricate core-id from DT semantics
From: |
Greg Kurz |
Subject: |
[Qemu-ppc] [PATCH RFC] spapr: disintricate core-id from DT semantics |
Date: |
Fri, 22 Jul 2016 13:10:36 +0200 |
User-agent: |
StGit/0.17.1-dirty |
The goal of this patch is to have a stable core-id which does not depend
on any DT related semantics, which involve non-obvious computations on
modern PowerPC server cpus.
With this patch, the DT core id is computed on-demand as:
(core-id / smp_threads) * smt
where smt is the number of threads per core in the host.
This formula should be consolidated in a helper since it is needed in
several places.
Other uses for core-id includes: compute a stable cpu_index (which
allows random order hotplug/unplug without breaking migration) and
NUMA.
Signed-off-by: Greg Kurz <address@hidden>
---
It was first suggested here:
https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg01727.html
and as option 1) in the following discussion on IRC:
<dwg> imammedo, basically the options are: 1) change core-ids to be
0, 1, .. n and compute cpu_index as core_id * threads + thread#, or
2) leave core-ids as they are and calculate cpu_index as
core-id / smt * threads + thread#
It is based on David's ppc-for-2.7 branch (commit bb6268f35f457).
It is lightly tested but I could at least do in-order hotplug/unplug.
hw/ppc/spapr.c | 10 +++++-----
hw/ppc/spapr_cpu_core.c | 24 +++++++++++-------------
2 files changed, 16 insertions(+), 18 deletions(-)
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 9193ac2c122b..fbbd0518edd4 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1815,10 +1815,11 @@ static void ppc_spapr_init(MachineState *machine)
spapr->cores = g_new0(Object *, spapr_max_cores);
for (i = 0; i < spapr_max_cores; i++) {
- int core_dt_id = i * smt;
+ int core_id = i * smp_threads;
sPAPRDRConnector *drc =
spapr_dr_connector_new(OBJECT(spapr),
- SPAPR_DR_CONNECTOR_TYPE_CPU,
core_dt_id);
+ SPAPR_DR_CONNECTOR_TYPE_CPU,
+ (core_id / smp_threads) * smt);
qemu_register_reset(spapr_drc_reset, drc);
@@ -1834,7 +1835,7 @@ static void ppc_spapr_init(MachineState *machine)
core = object_new(type);
object_property_set_int(core, smp_threads, "nr-threads",
&error_fatal);
- object_property_set_int(core, core_dt_id,
CPU_CORE_PROP_CORE_ID,
+ object_property_set_int(core, core_id, CPU_CORE_PROP_CORE_ID,
&error_fatal);
object_property_set_bool(core, true, "realized", &error_fatal);
}
@@ -2376,7 +2377,6 @@ static HotpluggableCPUList
*spapr_query_hotpluggable_cpus(MachineState *machine)
HotpluggableCPUList *head = NULL;
sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
int spapr_max_cores = max_cpus / smp_threads;
- int smt = kvmppc_smt_threads();
for (i = 0; i < spapr_max_cores; i++) {
HotpluggableCPUList *list_item = g_new0(typeof(*list_item), 1);
@@ -2386,7 +2386,7 @@ static HotpluggableCPUList
*spapr_query_hotpluggable_cpus(MachineState *machine)
cpu_item->type = spapr_get_cpu_core_type(machine->cpu_model);
cpu_item->vcpus_count = smp_threads;
cpu_props->has_core_id = true;
- cpu_props->core_id = i * smt;
+ cpu_props->core_id = i * smp_threads;
/* TODO: add 'has_node/node' here to describe
to which node core belongs */
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 4bfc96bd5a67..c04aaa47d7cd 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -103,7 +103,6 @@ static void spapr_core_release(DeviceState *dev, void
*opaque)
size_t size = object_type_get_instance_size(typename);
sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
CPUCore *cc = CPU_CORE(dev);
- int smt = kvmppc_smt_threads();
int i;
for (i = 0; i < cc->nr_threads; i++) {
@@ -117,7 +116,7 @@ static void spapr_core_release(DeviceState *dev, void
*opaque)
object_unparent(obj);
}
- spapr->cores[cc->core_id / smt] = NULL;
+ spapr->cores[cc->core_id / smp_threads] = NULL;
g_free(sc->threads);
object_unparent(OBJECT(dev));
@@ -128,18 +127,19 @@ void spapr_core_unplug(HotplugHandler *hotplug_dev,
DeviceState *dev,
{
sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
CPUCore *cc = CPU_CORE(dev);
+ int smt = kvmppc_smt_threads();
+ int index = cc->core_id / smp_threads;
sPAPRDRConnector *drc =
- spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core_id);
+ spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index * smt);
sPAPRDRConnectorClass *drck;
Error *local_err = NULL;
- int smt = kvmppc_smt_threads();
- int index = cc->core_id / smt;
int spapr_max_cores = max_cpus / smp_threads;
int i;
for (i = spapr_max_cores - 1; i > index; i--) {
if (spapr->cores[i]) {
- error_setg(errp, "core-id %d should be removed first", i * smt);
+ error_setg(errp, "core-id %d should be removed first",
+ i * smp_threads);
return;
}
}
@@ -168,11 +168,10 @@ void spapr_core_plug(HotplugHandler *hotplug_dev,
DeviceState *dev,
Error *local_err = NULL;
void *fdt = NULL;
int fdt_offset = 0;
- int index;
+ int index = cc->core_id / smp_threads;
int smt = kvmppc_smt_threads();
- drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core_id);
- index = cc->core_id / smt;
+ drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index * smt);
spapr->cores[index] = OBJECT(dev);
if (!smc->dr_cpu_enabled) {
@@ -226,7 +225,6 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev,
DeviceState *dev,
sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
int spapr_max_cores = max_cpus / smp_threads;
int index, i;
- int smt = kvmppc_smt_threads();
Error *local_err = NULL;
CPUCore *cc = CPU_CORE(dev);
char *base_core_type = spapr_get_cpu_core_type(machine->cpu_model);
@@ -247,12 +245,12 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev,
DeviceState *dev,
goto out;
}
- if (cc->core_id % smt) {
+ if (cc->core_id % smp_threads) {
error_setg(&local_err, "invalid core id %d\n", cc->core_id);
goto out;
}
- index = cc->core_id / smt;
+ index = cc->core_id / smp_threads;
if (index < 0 || index >= spapr_max_cores) {
error_setg(&local_err, "core id %d out of range", cc->core_id);
goto out;
@@ -266,7 +264,7 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev,
DeviceState *dev,
for (i = 0; i < index; i++) {
if (!spapr->cores[i]) {
error_setg(&local_err, "core-id %d should be added first",
- i * smt);
+ i * smp_threads);
goto out;
}
}
- [Qemu-ppc] [PATCH RFC] spapr: disintricate core-id from DT semantics,
Greg Kurz <=