softmmu/vl.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)
Preallocation in memory backends can be specified with either global
QEMU option "-mem-prealloc", or with per-backend property
"prealloc=true". In the latter case, however, the default for the
number of preallocation threads is not set to the number of vcpus, but
remains at 1 instead.
Fix it by setting the "prealloc-threads" sugar property of
"memory-backend" to the number of vcpus unconditionally.
Fixes: ffac16fab3 ("hostmem: introduce "prealloc-threads" property")
Signed-off-by: Denis Plotnikov <den-plotnikov@yandex-team.ru>
---
softmmu/vl.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/softmmu/vl.c b/softmmu/vl.c
index ff488ea3e7db..e392e226a2d3 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2300,14 +2300,17 @@ static void qemu_validate_options(void)
static void qemu_process_sugar_options(void)
{
- if (mem_prealloc) {
- char *val;
+ char *val;
- val = g_strdup_printf("%d",
- (uint32_t) qemu_opt_get_number(qemu_find_opts_singleton("smp-opts"), "cpus", 1));
- object_register_sugar_prop("memory-backend", "prealloc-threads", val,
- false);
- g_free(val);
+ val = g_strdup_printf("%d",
+ (uint32_t) qemu_opt_get_number(
+ qemu_find_opts_singleton("smp-opts"), "cpus", 1));
+
+ object_register_sugar_prop("memory-backend", "prealloc-threads", val,
+ false);
+ g_free(val);
+
+ if (mem_prealloc) {
object_register_sugar_prop("memory-backend", "prealloc", "on", false);
}
--
2.25.1
On 11/03/21 09:59, Denis Plotnikov wrote: > Preallocation in memory backends can be specified with either global > QEMU option "-mem-prealloc", or with per-backend property > "prealloc=true". In the latter case, however, the default for the > number of preallocation threads is not set to the number of vcpus, but > remains at 1 instead. > > Fix it by setting the "prealloc-threads" sugar property of > "memory-backend" to the number of vcpus unconditionally. > > Fixes: ffac16fab3 ("hostmem: introduce "prealloc-threads" property") > > Signed-off-by: Denis Plotnikov <den-plotnikov@yandex-team.ru> > --- > softmmu/vl.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/softmmu/vl.c b/softmmu/vl.c > index ff488ea3e7db..e392e226a2d3 100644 > --- a/softmmu/vl.c > +++ b/softmmu/vl.c > @@ -2300,14 +2300,17 @@ static void qemu_validate_options(void) > > static void qemu_process_sugar_options(void) > { > - if (mem_prealloc) { > - char *val; > + char *val; > > - val = g_strdup_printf("%d", > - (uint32_t) qemu_opt_get_number(qemu_find_opts_singleton("smp-opts"), "cpus", 1)); > - object_register_sugar_prop("memory-backend", "prealloc-threads", val, > - false); > - g_free(val); > + val = g_strdup_printf("%d", > + (uint32_t) qemu_opt_get_number( > + qemu_find_opts_singleton("smp-opts"), "cpus", 1)); > + > + object_register_sugar_prop("memory-backend", "prealloc-threads", val, > + false); > + g_free(val); > + > + if (mem_prealloc) { > object_register_sugar_prop("memory-backend", "prealloc", "on", false); > } > > Queued, thanks. Paolo
On 11/03/21 09:59, Denis Plotnikov wrote: > diff --git a/softmmu/vl.c b/softmmu/vl.c > index ff488ea3e7db..e392e226a2d3 100644 > --- a/softmmu/vl.c > +++ b/softmmu/vl.c > @@ -2300,14 +2300,17 @@ static void qemu_validate_options(void) > > static void qemu_process_sugar_options(void) > { > - if (mem_prealloc) { > - char *val; > + char *val; > > - val = g_strdup_printf("%d", > - (uint32_t) qemu_opt_get_number(qemu_find_opts_singleton("smp-opts"), "cpus", 1)); > - object_register_sugar_prop("memory-backend", "prealloc-threads", val, > - false); > - g_free(val); > + val = g_strdup_printf("%d", > + (uint32_t) qemu_opt_get_number( > + qemu_find_opts_singleton("smp-opts"), "cpus", 1)); > + > + object_register_sugar_prop("memory-backend", "prealloc-threads", val, > + false); > + g_free(val); > + > + if (mem_prealloc) { > object_register_sugar_prop("memory-backend", "prealloc", "on", false); > } Hi Denis, this patch breaks make check-qtest-arm: G_TEST_DBUS_DAEMON=/home/pbonzini/work/upstream/qemu/tests/dbus-vmstate-daemon.sh QTEST_QEMU_IMG=./qemu-img MALLOC_PERTURB_=45 QTEST_QEMU_BINARY=./qemu-system-arm /home/pbonzini/work/upstream/qemu/+bb/tests/qtest/npcm7xx_emc-test --tap -k # random seed: R02Sac2b21edc4fb48abab9f9723147ddbd5 1..6 # Start of arm tests # Start of npcm7xx_emc tests # Start of emc[0] tests # starting QEMU: exec ./qemu-system-arm -qtest unix:/tmp/qtest-839596.sock -qtest-log /dev/null -chardev socket,path=/tmp/qtest-839596.qmp,id=char0 -mon chardev=char0,mode=control -display none -machine quanta-gsj -accel qtest qemu-system-arm: Invalid SMP CPUs 1. The min CPUs supported by machine 'quanta-gsj' is 2 Paolo
On Thu, 11 Mar 2021 11:59:18 +0300 Denis Plotnikov <den-plotnikov@yandex-team.ru> wrote: > Preallocation in memory backends can be specified with either global > QEMU option "-mem-prealloc", or with per-backend property > "prealloc=true". In the latter case, however, the default for the > number of preallocation threads is not set to the number of vcpus, but > remains at 1 instead. > > Fix it by setting the "prealloc-threads" sugar property of > "memory-backend" to the number of vcpus unconditionally. well, number of prealloc-threads are policy that should be set by user. it was kept equal to vcpus for compat reasons with "-mem-prealloc", for if one goes with supplying memory backends explicitly, one is supposed to set prealloc-threads explicitly as well if default(==1) doesn't suit user. It could be equal to #vcpus or be a different numbers depending on host CPU configuration. That was intent when commit ffac16fab3 was introduced. Imagine one has a VM with a lot of VCPUs but not so much of of RAM, setting prealloc-threads to #VCPUs will be wasting CPU resources at least. > Fixes: ffac16fab3 ("hostmem: introduce "prealloc-threads" property") > > Signed-off-by: Denis Plotnikov <den-plotnikov@yandex-team.ru> > --- > softmmu/vl.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/softmmu/vl.c b/softmmu/vl.c > index ff488ea3e7db..e392e226a2d3 100644 > --- a/softmmu/vl.c > +++ b/softmmu/vl.c > @@ -2300,14 +2300,17 @@ static void qemu_validate_options(void) > > static void qemu_process_sugar_options(void) > { > - if (mem_prealloc) { > - char *val; > + char *val; > > - val = g_strdup_printf("%d", > - (uint32_t) qemu_opt_get_number(qemu_find_opts_singleton("smp-opts"), "cpus", 1)); > - object_register_sugar_prop("memory-backend", "prealloc-threads", val, > - false); > - g_free(val); > + val = g_strdup_printf("%d", > + (uint32_t) qemu_opt_get_number( > + qemu_find_opts_singleton("smp-opts"), "cpus", 1)); > + > + object_register_sugar_prop("memory-backend", "prealloc-threads", val, > + false); > + g_free(val); > + > + if (mem_prealloc) { > object_register_sugar_prop("memory-backend", "prealloc", "on", false); > } >
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