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[PATCH 7/7] spapr: Set VSMT to smp_threads by default
From: |
Greg Kurz |
Subject: |
[PATCH 7/7] spapr: Set VSMT to smp_threads by default |
Date: |
Thu, 03 Oct 2019 14:02:00 +0200 |
User-agent: |
StGit/unknown-version |
Support for setting VSMT is available in KVM since linux-4.13. Most distros
that support KVM on POWER already have it. It thus seem reasonable enough
to have the default machine to set VSMT to smp_threads.
This brings contiguous VCPU ids and thus brings their upper bound down to
the machine's max_cpus. This is especially useful for XIVE KVM devices,
which may thus allocate only one VP descriptor per VCPU.
Signed-off-by: Greg Kurz <address@hidden>
---
hw/ppc/spapr.c | 7 ++++++-
include/hw/ppc/spapr.h | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 8f59f08c102e..473ce1d04775 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2503,6 +2503,7 @@ static CPUArchId *spapr_find_cpu_slot(MachineState *ms,
uint32_t id, int *idx)
static void spapr_set_vsmt_mode(SpaprMachineState *spapr, Error **errp)
{
MachineState *ms = MACHINE(spapr);
+ SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
Error *local_err = NULL;
bool vsmt_user = !!spapr->vsmt;
int kvm_smt = kvmppc_smt_threads();
@@ -2529,7 +2530,7 @@ static void spapr_set_vsmt_mode(SpaprMachineState *spapr,
Error **errp)
goto out;
}
/* In this case, spapr->vsmt has been set by the command line */
- } else {
+ } else if (!smc->smp_threads_vsmt) {
/*
* Default VSMT value is tricky, because we need it to be as
* consistent as possible (for migration), but this requires
@@ -2538,6 +2539,8 @@ static void spapr_set_vsmt_mode(SpaprMachineState *spapr,
Error **errp)
* overwhelmingly common case in production systems.
*/
spapr->vsmt = MAX(8, smp_threads);
+ } else {
+ spapr->vsmt = smp_threads;
}
/* KVM: If necessary, set the SMT mode: */
@@ -4452,6 +4455,7 @@ static void spapr_machine_class_init(ObjectClass *oc,
void *data)
smc->irq = &spapr_irq_dual;
smc->dr_phb_enabled = true;
smc->linux_pci_probe = true;
+ smc->smp_threads_vsmt = true;
}
static const TypeInfo spapr_machine_info = {
@@ -4519,6 +4523,7 @@ static void spapr_machine_4_1_class_options(MachineClass
*mc)
spapr_machine_4_2_class_options(mc);
smc->linux_pci_probe = false;
+ smc->smp_threads_vsmt = false;
compat_props_add(mc->compat_props, hw_compat_4_1, hw_compat_4_1_len);
compat_props_add(mc->compat_props, compat, G_N_ELEMENTS(compat));
}
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index cbd1a4c9f390..2009eb64f9cb 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -122,6 +122,7 @@ struct SpaprMachineClass {
bool broken_host_serial_model; /* present real host info to the guest */
bool pre_4_1_migration; /* don't migrate hpt-max-page-size */
bool linux_pci_probe;
+ bool smp_threads_vsmt; /* set VSMT to smp_threads by default */
void (*phb_placement)(SpaprMachineState *spapr, uint32_t index,
uint64_t *buid, hwaddr *pio,
- Re: [PATCH 2/7] spapr, xive: Turn "nr-ends" property into "nr-servers" property, (continued)
- [PATCH 3/7] spapr, xics, xive: Drop nr_servers argument in DT-related functions, Greg Kurz, 2019/10/03
- [PATCH RFC 4/7] linux-headers: Update against 5.3-rc2, Greg Kurz, 2019/10/03
- [PATCH 5/7] spapr/xics: Configure number of servers in KVM, Greg Kurz, 2019/10/03
- [PATCH 6/7] spapr/xive: Configure number of servers in KVM, Greg Kurz, 2019/10/03
- [PATCH 7/7] spapr: Set VSMT to smp_threads by default,
Greg Kurz <=