eee064d954
In qemu-server, we already allocate 2 * $mem_size + 500 MiB for driver
state (which was 32 MiB long ago according to git history). It seems
likely that the 30 MiB cutoff in the savevm-async implementation was
chosen based on that.
In bug #4476 [0], another issue caused the iteration to not make any
progress and the state file filled up all the way to the 30 MiB +
pending_size cutoff. Since the guest is not stopped immediately after
the check, it can still dirty some RAM and the current cutoff is not
enough for a reproducer VM (was done while bug #4476 still was not
fixed), dirtying memory with
> stress-ng -B 2 --bigheap-growth 64.0M'
After entering the final stage, savevm actually filled up the state
file completely, leading to an I/O error. It's probably the same
scenario as reported in the bug report, the error message was fixed in
commit a020815 ("savevm-async: fix function name in error message")
after the bug report.
If not for the bug, the cutoff will only be reached by a VM that's
dirtying RAM faster than can be written to the storage, so increase
the cutoff to 100 MiB to have a bigger chance to finish successfully,
while still trying to not increase downtime too much for
non-hibernation snapshots.
[0]: https://bugzilla.proxmox.com/show_bug.cgi?id=4476
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
36 lines
1.2 KiB
Diff
36 lines
1.2 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Stefan Reiter <s.reiter@proxmox.com>
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Date: Wed, 26 May 2021 17:36:55 +0200
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Subject: [PATCH] PVE: savevm-async: register yank before
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migration_incoming_state_destroy
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Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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migration/savevm-async.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/migration/savevm-async.c b/migration/savevm-async.c
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index a38e7351c1..0b1b60c6ae 100644
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--- a/migration/savevm-async.c
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+++ b/migration/savevm-async.c
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@@ -20,6 +20,7 @@
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#include "qemu/timer.h"
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#include "qemu/main-loop.h"
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#include "qemu/rcu.h"
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+#include "qemu/yank.h"
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/* #define DEBUG_SAVEVM_STATE */
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@@ -521,6 +522,10 @@ int load_snapshot_from_blockdev(const char *filename, Error **errp)
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dirty_bitmap_mig_before_vm_start();
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qemu_fclose(f);
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+
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+ /* state_destroy assumes a real migration which would have added a yank */
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+ yank_register_instance(MIGRATION_YANK_INSTANCE, &error_abort);
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+
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migration_incoming_state_destroy();
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if (ret < 0) {
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error_setg_errno(errp, -ret, "Error while loading VM state");
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