Re: [PATCH v2 00/11] migration: Some enhancements and cleanups for 10.1

[Peter Xu <peterx@redhat.com>]

On Mon, Jun 09, 2025 at 12:18:44PM -0400, Peter Xu wrote:
> v2:
> - Collected R-bs
> - Avoid using "\b" in HMP dumps [Markus, Dave]
> 
> The series is based on a small patch from Yanfei Xu here:
> 
> Based-on: <20250514115827.3216082-1-yanfei.xu@bytedance.com>
> https://lore.kernel.org/r/20250514115827.3216082-1-yanfei.xu@bytedance.com
> 
> This is a series that collected many of either enhancements or cleanups I
> got for QEMU 10.1, which almost came from when working on the last patch.
> 
> The last patch, which is a oneliner, can further reduce 10% postcopy page
> fault latency with preempt mode enabled.
> 
>       Before: 268.00us (+-1.87%)
>       After:  232.67us (+-2.01%)
> 
> The patch layout is as following:
> 
> Patch 1:         A follow up of HMP change for "info migrate", per
>                  suggestion from Dave
> Patch 2:         Yet another HMP fix for blocktime displays
> Patch 3-10:      Cleanups everywhere, especially please take a look at
>                  patch 10 which changes the core switchover decision logic
> Patch 11:        The one-liner optimization
> 
> Comments welcomed, thanks.
> 
> Peter Xu (11):
>   migration/hmp: Reorg "info migrate" once more
>   migration/hmp: Fix postcopy-blocktime per-vCPU results
>   migration/docs: Move docs for postcopy blocktime feature
>   migration/bg-snapshot: Do not check for SKIP in iterator
>   migration: Drop save_live_complete_postcopy hook
>   migration: Rename save_live_complete_precopy to save_complete
>   migration: qemu_savevm_complete*() helpers
>   migration/ram: One less indent for ram_find_and_save_block()
>   migration/ram: Add tracepoints for ram_save_complete()
>   migration: Rewrite the migration complete detect logic
>   migration/postcopy: Avoid clearing dirty bitmap for postcopy too

There're two checkpatch issues need fixing.  Two fixups will be needed as
below, one remove a space, one fix 80 chars.  I'll squash if I'm sending
new versions.

Sorry for the noise.

===8<===

From 25356e1262006fd668ba4e29b01325b5e784e19a Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Wed, 11 Jun 2025 17:23:00 -0400
Subject: [PATCH] fixup! migration/hmp: Fix postcopy-blocktime per-vCPU results

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration-hmp-cmds.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 6c36e202a0..867e017b32 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -212,7 +212,7 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
         const char *sep = "";
         int count = 0;
 
-        monitor_printf(mon, "Postcopy vCPU Blocktime (ms): \n [");
+        monitor_printf(mon, "Postcopy vCPU Blocktime (ms):\n [");
 
         while (item) {
             monitor_printf(mon, "%s%"PRIu32, sep, item->value);
-- 
2.49.0


From 58dfb3e311fb477732d0f109886d02adcb439e14 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Wed, 11 Jun 2025 17:23:38 -0400
Subject: [PATCH] fixup! migration: Rewrite the migration complete detect logic

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/migration/migration.c b/migration/migration.c
index 1a26a4bfef..923400f801 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3460,7 +3460,8 @@ static MigIterateState migration_iteration_run(MigrationState *s)
         if (pending_size < s->threshold_size) {
             qemu_savevm_state_pending_exact(&must_precopy, &can_postcopy);
             pending_size = must_precopy + can_postcopy;
-            trace_migrate_pending_exact(pending_size, must_precopy, can_postcopy);
+            trace_migrate_pending_exact(pending_size, must_precopy,
+                                        can_postcopy);
         }
 
         /* Should we switch to postcopy now? */
-- 
2.49.0


-- 
Peter Xu