At the moment only a whole CPU core can be assigned to a KVM. Since
POWER7/8 support several threads per core, we want all threads of a core
to go to the same KVM so every time we run QEMU with -enable-kvm on
POWER, we have to add -smp X,threads=(4|8)" (4 for POWER7 and
8 for POWER8).
This patch tries to read smp_threads number from an accelerator and
falls back to the default value (1) if the accelerator did not care
to change it.
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
(!!!)
The usual question - what would be the normal way of doing this?
What does this patch break? I cannot think of anything right now.
---
target-ppc/kvm.c | 6 ++++++
vl.c | 29 ++++++++++++++++-------------
2 files changed, 22 insertions(+), 13 deletions(-)
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 10d0cd9..80c0386 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -109,6 +109,12 @@ int kvm_arch_init(KVMState *s)
"VM to stall at times!\n");
}
+ if (!smp_threads) {
+ smp_threads = cap_ppc_smt;
+ } else {
+ smp_threads = MIN(smp_threads, cap_ppc_smt);
+ }
+
kvm_ppc_register_host_cpu_type();
return 0;
diff --git a/vl.c b/vl.c
index 4ad15b8..97fa203 100644
--- a/vl.c
+++ b/vl.c
@@ -210,7 +210,7 @@ int singlestep = 0;
int smp_cpus = 1;
int max_cpus = 0;
int smp_cores = 1;
-int smp_threads = 1;
+int smp_threads = 0;
#ifdef CONFIG_VNC
const char *vnc_display;
#endif
@@ -1395,7 +1395,9 @@ static void smp_parse(QemuOpts *opts)
if (cpus == 0 || sockets == 0) {
sockets = sockets > 0 ? sockets : 1;
cores = cores > 0 ? cores : 1;
- threads = threads > 0 ? threads : 1;
+ if (!threads) {
+ threads = smp_threads > 0 ? smp_threads : 1;
+ }
if (cpus == 0) {
cpus = cores * threads * sockets;
}
@@ -1413,7 +1415,8 @@ static void smp_parse(QemuOpts *opts)
smp_cpus = cpus;
smp_cores = cores > 0 ? cores : 1;
smp_threads = threads > 0 ? threads : 1;
-
+ } else if (!smp_threads) {
+ smp_threads = 1;
}
if (max_cpus == 0) {
@@ -3880,16 +3883,6 @@ int main(int argc, char **argv, char **envp)
data_dir[data_dir_idx++] = CONFIG_QEMU_DATADIR;
}
- smp_parse(qemu_opts_find(qemu_find_opts("smp-opts"), NULL));
-
- machine->max_cpus = machine->max_cpus ?: 1; /* Default to UP */
- if (smp_cpus > machine->max_cpus) {
- fprintf(stderr, "Number of SMP cpus requested (%d), exceeds max cpus "
- "supported by machine `%s' (%d)\n", smp_cpus, machine->name,
- machine->max_cpus);
- exit(1);
- }
-
/*
* Get the default machine options from the machine if it is not already
* specified either by the configuration file or by the command line.
@@ -4039,6 +4032,16 @@ int main(int argc, char **argv, char **envp)
configure_accelerator();
+ smp_parse(qemu_opts_find(qemu_find_opts("smp-opts"), NULL));
+
+ machine->max_cpus = machine->max_cpus ?: 1; /* Default to UP */
+ if (smp_cpus > machine->max_cpus) {
+ fprintf(stderr, "Number of SMP cpus requested (%d), exceeds max cpus "
+ "supported by machine `%s' (%d)\n", smp_cpus, machine->name,
+ machine->max_cpus);
+ exit(1);
+ }
+
if (!qtest_enabled() && qtest_chrdev) {
qtest_init();
}
--
1.8.4.rc4
