* [PATCH v9 1/3] multifd: Create property multifd-flush-after-each-section
2023-04-26 18:18 [PATCH v9 0/3] Eliminate multifd flush Juan Quintela
@ 2023-04-26 18:18 ` Juan Quintela
2023-04-26 18:19 ` [PATCH v9 2/3] multifd: Protect multifd_send_sync_main() calls Juan Quintela
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Juan Quintela @ 2023-04-26 18:18 UTC (permalink / raw)
To: qemu-devel
Cc: Philippe Mathieu-Daudé, Marcel Apfelbaum, Peter Xu,
Juan Quintela, Leonardo Bras, Yanan Wang, Eduardo Habkost,
Dr . David Alan Gilbert
We used to flush all channels at the end of each RAM section
sent. That is not needed, so preparing to only flush after a full
iteration through all the RAM.
Default value of the property is false. But we return "true" in
migrate_multifd_flush_after_each_section() until we implement the code
in following patches.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
Rename each-iteration to after-each-section
Rename multifd-sync-after-each-section to
multifd-flush-after-each-section
Move to machine-8.0 (peter)
---
hw/core/machine.c | 4 +++-
migration/migration.c | 2 ++
migration/migration.h | 12 ++++++++++++
migration/options.c | 11 +++++++++++
migration/options.h | 1 +
5 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 2ce97a5d3b..47a34841a5 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -39,7 +39,9 @@
#include "hw/virtio/virtio.h"
#include "hw/virtio/virtio-pci.h"
-GlobalProperty hw_compat_8_0[] = {};
+GlobalProperty hw_compat_8_0[] = {
+ { "migration", "multifd-flush-after-each-section", "on"},
+};
const size_t hw_compat_8_0_len = G_N_ELEMENTS(hw_compat_8_0);
GlobalProperty hw_compat_7_2[] = {
diff --git a/migration/migration.c b/migration/migration.c
index 22e8586623..e82aa69842 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3344,6 +3344,8 @@ static Property migration_properties[] = {
send_section_footer, true),
DEFINE_PROP_BOOL("decompress-error-check", MigrationState,
decompress_error_check, true),
+ DEFINE_PROP_BOOL("multifd-flush-after-each-section", MigrationState,
+ multifd_flush_after_each_section, true),
DEFINE_PROP_UINT8("x-clear-bitmap-shift", MigrationState,
clear_bitmap_shift, CLEAR_BITMAP_SHIFT_DEFAULT),
DEFINE_PROP_BOOL("x-preempt-pre-7-2", MigrationState,
diff --git a/migration/migration.h b/migration/migration.h
index 2b71df8617..e2247d708f 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -404,6 +404,18 @@ struct MigrationState {
*/
bool preempt_pre_7_2;
+ /*
+ * flush every channel after each section sent.
+ *
+ * This assures that we can't mix pages from one iteration through
+ * ram pages with pages for the following iteration. We really
+ * only need to do this flush after we have go through all the
+ * dirty pages. For historical reasons, we do that after each
+ * section. This is suboptimal (we flush too many times).
+ * Default value is false. Setting this property has no effect
+ * until the patch that removes this comment. (since 8.1)
+ */
+ bool multifd_flush_after_each_section;
/*
* This decides the size of guest memory chunk that will be used
* to track dirty bitmap clearing. The size of memory chunk will
diff --git a/migration/options.c b/migration/options.c
index c6030587cf..b9d54b4ef7 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -217,6 +217,17 @@ bool migrate_zero_copy_send(void)
/* pseudo capabilities */
+bool migrate_multifd_flush_after_each_section(void)
+{
+ MigrationState *s = migrate_get_current();
+
+ /*
+ * Until the patch that remove this comment, we always return that
+ * the property is enabled.
+ */
+ return true || s->multifd_flush_after_each_section;
+}
+
bool migrate_postcopy(void)
{
return migrate_postcopy_ram() || migrate_dirty_bitmaps();
diff --git a/migration/options.h b/migration/options.h
index 89067e59a0..9b9ea0cde8 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -52,6 +52,7 @@ bool migrate_zero_copy_send(void);
* check, but they are not a capability.
*/
+bool migrate_multifd_flush_after_each_section(void);
bool migrate_postcopy(void);
bool migrate_tls(void);
--
2.40.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v9 2/3] multifd: Protect multifd_send_sync_main() calls
2023-04-26 18:18 [PATCH v9 0/3] Eliminate multifd flush Juan Quintela
2023-04-26 18:18 ` [PATCH v9 1/3] multifd: Create property multifd-flush-after-each-section Juan Quintela
@ 2023-04-26 18:19 ` Juan Quintela
2023-04-26 18:19 ` [PATCH v9 3/3] multifd: Only flush once each full round of memory Juan Quintela
2023-04-26 19:49 ` [PATCH v9 0/3] Eliminate multifd flush Peter Xu
3 siblings, 0 replies; 5+ messages in thread
From: Juan Quintela @ 2023-04-26 18:19 UTC (permalink / raw)
To: qemu-devel
Cc: Philippe Mathieu-Daudé, Marcel Apfelbaum, Peter Xu,
Juan Quintela, Leonardo Bras, Yanan Wang, Eduardo Habkost,
Dr . David Alan Gilbert
We only need to do that on the ram_save_iterate() call on sending and
on destination when we get a RAM_SAVE_FLAG_EOS.
In setup() and complete() we need to synch in both new and old cases,
so don't add a check there.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
---
Remove the wrappers that we take out on patch 5.
---
migration/ram.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 01356f60a4..1e2414d681 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3394,9 +3394,11 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
out:
if (ret >= 0
&& migration_is_setup_or_active(migrate_get_current()->state)) {
- ret = multifd_send_sync_main(rs->pss[RAM_CHANNEL_PRECOPY].pss_channel);
- if (ret < 0) {
- return ret;
+ if (migrate_multifd_flush_after_each_section()) {
+ ret = multifd_send_sync_main(rs->pss[RAM_CHANNEL_PRECOPY].pss_channel);
+ if (ret < 0) {
+ return ret;
+ }
}
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
@@ -4153,7 +4155,9 @@ int ram_load_postcopy(QEMUFile *f, int channel)
case RAM_SAVE_FLAG_EOS:
/* normal exit */
- multifd_recv_sync_main();
+ if (migrate_multifd_flush_after_each_section()) {
+ multifd_recv_sync_main();
+ }
break;
default:
error_report("Unknown combination of migration flags: 0x%x"
@@ -4424,7 +4428,9 @@ static int ram_load_precopy(QEMUFile *f)
break;
case RAM_SAVE_FLAG_EOS:
/* normal exit */
- multifd_recv_sync_main();
+ if (migrate_multifd_flush_after_each_section()) {
+ multifd_recv_sync_main();
+ }
break;
default:
if (flags & RAM_SAVE_FLAG_HOOK) {
--
2.40.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v9 3/3] multifd: Only flush once each full round of memory
2023-04-26 18:18 [PATCH v9 0/3] Eliminate multifd flush Juan Quintela
2023-04-26 18:18 ` [PATCH v9 1/3] multifd: Create property multifd-flush-after-each-section Juan Quintela
2023-04-26 18:19 ` [PATCH v9 2/3] multifd: Protect multifd_send_sync_main() calls Juan Quintela
@ 2023-04-26 18:19 ` Juan Quintela
2023-04-26 19:49 ` [PATCH v9 0/3] Eliminate multifd flush Peter Xu
3 siblings, 0 replies; 5+ messages in thread
From: Juan Quintela @ 2023-04-26 18:19 UTC (permalink / raw)
To: qemu-devel
Cc: Philippe Mathieu-Daudé, Marcel Apfelbaum, Peter Xu,
Juan Quintela, Leonardo Bras, Yanan Wang, Eduardo Habkost
We need to add a new flag to mean to flush at that point.
Notice that we still flush at the end of setup and at the end of
complete stages.
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
Add missing qemu_fflush(), now it passes all tests always.
In the previous version, the check that changes the default value to
false got lost in some rebase. Get it back.
---
migration/migration.c | 2 +-
migration/migration.h | 3 +--
migration/options.c | 6 +-----
migration/ram.c | 28 +++++++++++++++++++++++++++-
4 files changed, 30 insertions(+), 9 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index e82aa69842..e504f30c2e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3345,7 +3345,7 @@ static Property migration_properties[] = {
DEFINE_PROP_BOOL("decompress-error-check", MigrationState,
decompress_error_check, true),
DEFINE_PROP_BOOL("multifd-flush-after-each-section", MigrationState,
- multifd_flush_after_each_section, true),
+ multifd_flush_after_each_section, false),
DEFINE_PROP_UINT8("x-clear-bitmap-shift", MigrationState,
clear_bitmap_shift, CLEAR_BITMAP_SHIFT_DEFAULT),
DEFINE_PROP_BOOL("x-preempt-pre-7-2", MigrationState,
diff --git a/migration/migration.h b/migration/migration.h
index e2247d708f..3a918514e7 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -412,8 +412,7 @@ struct MigrationState {
* only need to do this flush after we have go through all the
* dirty pages. For historical reasons, we do that after each
* section. This is suboptimal (we flush too many times).
- * Default value is false. Setting this property has no effect
- * until the patch that removes this comment. (since 8.1)
+ * Default value is false. (since 8.1)
*/
bool multifd_flush_after_each_section;
/*
diff --git a/migration/options.c b/migration/options.c
index b9d54b4ef7..78bfcc8ec0 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -221,11 +221,7 @@ bool migrate_multifd_flush_after_each_section(void)
{
MigrationState *s = migrate_get_current();
- /*
- * Until the patch that remove this comment, we always return that
- * the property is enabled.
- */
- return true || s->multifd_flush_after_each_section;
+ return s->multifd_flush_after_each_section;
}
bool migrate_postcopy(void)
diff --git a/migration/ram.c b/migration/ram.c
index 1e2414d681..e9dcda8b9d 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -86,6 +86,7 @@
#define RAM_SAVE_FLAG_XBZRLE 0x40
/* 0x80 is reserved in qemu-file.h for RAM_SAVE_FLAG_HOOK */
#define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100
+#define RAM_SAVE_FLAG_MULTIFD_FLUSH 0x200
/* We can't use any flag that is bigger than 0x200 */
int (*xbzrle_encode_buffer_func)(uint8_t *, uint8_t *, int,
@@ -1581,6 +1582,7 @@ retry:
* associated with the search process.
*
* Returns:
+ * <0: An error happened
* PAGE_ALL_CLEAN: no dirty page found, give up
* PAGE_TRY_AGAIN: no dirty page found, retry for next block
* PAGE_DIRTY_FOUND: dirty page found
@@ -1608,6 +1610,15 @@ static int find_dirty_block(RAMState *rs, PageSearchStatus *pss)
pss->page = 0;
pss->block = QLIST_NEXT_RCU(pss->block, next);
if (!pss->block) {
+ if (!migrate_multifd_flush_after_each_section()) {
+ QEMUFile *f = rs->pss[RAM_CHANNEL_PRECOPY].pss_channel;
+ int ret = multifd_send_sync_main(f);
+ if (ret < 0) {
+ return ret;
+ }
+ qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
+ qemu_fflush(f);
+ }
/*
* If memory migration starts over, we will meet a dirtied page
* which may still exists in compression threads's ring, so we
@@ -2600,6 +2611,9 @@ static int ram_find_and_save_block(RAMState *rs)
break;
} else if (res == PAGE_TRY_AGAIN) {
continue;
+ } else if (res < 0) {
+ pages = res;
+ break;
}
}
}
@@ -3286,6 +3300,10 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
return ret;
}
+ if (!migrate_multifd_flush_after_each_section()) {
+ qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
+ }
+
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
qemu_fflush(f);
@@ -3471,6 +3489,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
return ret;
}
+ if (!migrate_multifd_flush_after_each_section()) {
+ qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
+ }
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
qemu_fflush(f);
@@ -4152,7 +4173,9 @@ int ram_load_postcopy(QEMUFile *f, int channel)
}
decompress_data_with_multi_threads(f, page_buffer, len);
break;
-
+ case RAM_SAVE_FLAG_MULTIFD_FLUSH:
+ multifd_recv_sync_main();
+ break;
case RAM_SAVE_FLAG_EOS:
/* normal exit */
if (migrate_multifd_flush_after_each_section()) {
@@ -4426,6 +4449,9 @@ static int ram_load_precopy(QEMUFile *f)
break;
}
break;
+ case RAM_SAVE_FLAG_MULTIFD_FLUSH:
+ multifd_recv_sync_main();
+ break;
case RAM_SAVE_FLAG_EOS:
/* normal exit */
if (migrate_multifd_flush_after_each_section()) {
--
2.40.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v9 0/3] Eliminate multifd flush
2023-04-26 18:18 [PATCH v9 0/3] Eliminate multifd flush Juan Quintela
` (2 preceding siblings ...)
2023-04-26 18:19 ` [PATCH v9 3/3] multifd: Only flush once each full round of memory Juan Quintela
@ 2023-04-26 19:49 ` Peter Xu
3 siblings, 0 replies; 5+ messages in thread
From: Peter Xu @ 2023-04-26 19:49 UTC (permalink / raw)
To: Juan Quintela
Cc: qemu-devel, Philippe Mathieu-Daudé, Marcel Apfelbaum,
Leonardo Bras, Yanan Wang, Eduardo Habkost
On Wed, Apr 26, 2023 at 08:18:58PM +0200, Juan Quintela wrote:
> Juan Quintela (3):
> multifd: Create property multifd-flush-after-each-section
> multifd: Protect multifd_send_sync_main() calls
> multifd: Only flush once each full round of memory
Acked-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
^ permalink raw reply [flat|nested] 5+ messages in thread