On Tue, May 23, 2017 at 02:31:07PM +0300, Alexey Perevalov wrote:
This patch adds request to kernel space for UFFD_FEATURE_THREAD_ID,
in case when this feature is provided by kernel.
PostcopyBlocktimeContext is incapsulated inside postcopy-ram.c,
due to it's postcopy only feature.
Also it defines PostcopyBlocktimeContext's instance live time.
Information from PostcopyBlocktimeContext instance will be provided
much after postcopy migration end, instance of PostcopyBlocktimeContext
will live till QEMU exit, but part of it (vcpu_addr,
page_fault_vcpu_time) used only during calculation, will be released
when postcopy ended or failed.
To enable postcopy blocktime calculation on destination, need to request
proper capabiltiy (Patch for documentation will be at the tail of the patch
set).
As an example following command enable that capability, assume QEMU was
started with
-chardev socket,id=charmonitor,path=/var/lib/migrate-vm-monitor.sock
option to control it
address@hidden "{\"execute\" : \"qmp_capabilities\"}\r\n \
{\"execute\": \"migrate-set-capabilities\" , \"arguments\": {
\"capabilities\": [ { \"capability\": \"postcopy-blocktime\", \"state\":
true } ] } }" | nc -U /var/lib/migrate-vm-monitor.sock
Or just with HMP
(qemu) migrate_set_capability postcopy-blocktime on
Signed-off-by: Alexey Perevalov <address@hidden>
---
include/migration/migration.h | 8 +++++
migration/postcopy-ram.c | 80 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+)
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 2951253..449cb07 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -57,6 +57,8 @@ enum mig_rp_message_type {
typedef QLIST_HEAD(, LoadStateEntry) LoadStateEntry_Head;
+struct PostcopyBlocktimeContext;
+
/* State for the incoming migration */
struct MigrationIncomingState {
QEMUFile *from_src_file;
@@ -97,6 +99,12 @@ struct MigrationIncomingState {
/* See savevm.c */
LoadStateEntry_Head loadvm_handlers;
+
+ /*
+ * PostcopyBlocktimeContext to keep information for postcopy
+ * live migration, to calculate vCPU block time
+ * */
+ struct PostcopyBlocktimeContext *blocktime_ctx;
};
MigrationIncomingState *migration_incoming_get_current(void);
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 4f3f495..5435a40 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -59,6 +59,73 @@ struct PostcopyDiscardState {
#include <sys/eventfd.h>
#include <linux/userfaultfd.h>
+typedef struct PostcopyBlocktimeContext {
+ /* time when page fault initiated per vCPU */
+ int64_t *page_fault_vcpu_time;
+ /* page address per vCPU */
+ uint64_t *vcpu_addr;
+ int64_t total_blocktime;
+ /* blocktime per vCPU */
+ int64_t *vcpu_blocktime;
+ /* point in time when last page fault was initiated */
+ int64_t last_begin;
+ /* number of vCPU are suspended */
+ int smp_cpus_down;
+
+ /*
+ * Handler for exit event, necessary for
+ * releasing whole blocktime_ctx
+ */
+ Notifier exit_notifier;
+ /*
+ * Handler for postcopy event, necessary for
+ * releasing unnecessary part of blocktime_ctx
+ */
+ Notifier postcopy_notifier;
+} PostcopyBlocktimeContext;
+
+static void destroy_blocktime_context(struct PostcopyBlocktimeContext *ctx)
+{
+ g_free(ctx->page_fault_vcpu_time);
+ g_free(ctx->vcpu_addr);
+ g_free(ctx->vcpu_blocktime);
+ g_free(ctx);
+}
+
+static void postcopy_migration_cb(Notifier *n, void *data)
+{
+ PostcopyBlocktimeContext *ctx = container_of(n, PostcopyBlocktimeContext,
+ postcopy_notifier);
+ MigrationState *s = data;
+ if (migration_has_finished(s) || migration_has_failed(s)) {
+ g_free(ctx->page_fault_vcpu_time);
+ /* g_free is NULL robust */
+ ctx->page_fault_vcpu_time = NULL;
+ g_free(ctx->vcpu_addr);
+ ctx->vcpu_addr = NULL;
+ }
+}
+
+static void migration_exit_cb(Notifier *n, void *data)
+{
+ PostcopyBlocktimeContext *ctx = container_of(n, PostcopyBlocktimeContext,
+ exit_notifier);
+ destroy_blocktime_context(ctx);
+}
+
+static struct PostcopyBlocktimeContext *blocktime_context_new(void)
+{
+ PostcopyBlocktimeContext *ctx = g_new0(PostcopyBlocktimeContext, 1);
+ ctx->page_fault_vcpu_time = g_new0(int64_t, smp_cpus);
+ ctx->vcpu_addr = g_new0(uint64_t, smp_cpus);
+ ctx->vcpu_blocktime = g_new0(int64_t, smp_cpus);
+
+ ctx->exit_notifier.notify = migration_exit_cb;
+ ctx->postcopy_notifier.notify = postcopy_migration_cb;
+ qemu_add_exit_notifier(&ctx->exit_notifier);
+ add_migration_state_change_notifier(&ctx->postcopy_notifier);
I think we just need a global MAX_VCPUS macro, then we can just make
the whole struct static. But I admit this is out of topic for current
thread. The point is indeed I see no much point on such fine-grained
management of memory on this... only for a summary of, say a maximum
of 1K vcpus, no more than 8B*3*1K=24KB memory...
IMHO This just made things complicated.
+ return ctx;
+}
/**
* receive_ufd_features: check userfault fd features, to request only
supported
@@ -151,6 +218,19 @@ static bool ufd_check_and_apply(int ufd,
MigrationIncomingState *mis)
}
}
+#ifdef UFFD_FEATURE_THREAD_ID
+ if (migrate_postcopy_blocktime() && mis &&
+ UFFD_FEATURE_THREAD_ID & supported_features) {
(indent)
+ /* kernel supports that feature */
+ /* don't create blocktime_context if it exists */
+ if (!mis->blocktime_ctx) {
If it does existed, then maybe we'll have problem - in the state
change notifier we cleaned up ->page_fault_vcpu_time and ->vcpu_addr,
but blocktime_ctx was there. So will it possible when we reached here
we'll get blocktime_ctx != NULL but
blocktime_ctx->page_fault_vcpu_time == NULL and also
blocktime_ctx->vcpu_addr == NULL?
Maybe we can just drop the state change notifier, and one single exit
notifier would be enough to cleanup everything?