Re: [Qemu-devel] [PATCH] Add warmup phase for live migration of large memory apps

[Shribman, Aidan]

> From: Juan Quintela [mailto:address@hidden 
> 
> > If there are no additional dirty pages to be sent
> > i.e. ram_save_remaining() == 0 then the migration *will* converge
> > (even though we don't want it to) see:
> 
> This should be a really idle guest to have that O:-)
> 
> But if that is the whole problem, I would change the code to make the
> case of max_downtime == 0 to mean that migration didn't converge.
> 

I agree this would be fine as surrogate for the warmup patch as I proposed. New 
patch based on your's / Anthony's suggestion:

---
diff --git a/arch_init.c b/arch_init.c
index 4486925..9a35411 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -295,7 +295,8 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
void *opaque)
 
     expected_time = ram_save_remaining() * TARGET_PAGE_SIZE / bwidth;
 
-    return (stage == 2) && (expected_time <= migrate_max_downtime());
+    return (stage == 2) && migrate_max_downtime() &&
+        (expected_time <= migrate_max_downtime());
 }
 
 static inline void *host_from_stream_offset(QEMUFile *f,
---

Best,
Aidan