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Re: [Qemu-devel] [PATCH 04/27] add a version number to ram_list
From: |
Juan Quintela |
Subject: |
Re: [Qemu-devel] [PATCH 04/27] add a version number to ram_list |
Date: |
Thu, 26 Jul 2012 11:19:09 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) |
Michael Roth <address@hidden> wrote:
> On Tue, Jul 24, 2012 at 08:36:29PM +0200, Juan Quintela wrote:
>> From: Umesh Deshpande <address@hidden>
>>
>> This will be used to detect if last_block might have become invalid
>> across different calls to ram_save_live.
>
> Was it a bug in the old code to not do this? In the unthreaded version
> it looks like last_block could still become invalid between iterations if it
> was removed in the meantime, so I'm trying to understand why it's needed
> now.
Old code assumed that we _never_ do hotplug/unplug of anything during
migration (I am still not convinced that everything works if we plug
some devices, but now at least memory works).
> And why do we re-sort when this happens? The old implementation didn't
> seem to place any guarantees on the block ordering beyond the initial
> sorting by block->idstr. After that they were sent in MRU order.
It is a "subtle" attempt to try to get the memory in order when we
suspend to disk. So we could compare two files done while we were
stopped. And no, I didn't liked when it was introduced.
Later, Juan.
- [Qemu-devel] [RFC 00/27] Migration thread (WIP), Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 01/27] buffered_file: g_realloc() can't fail, Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 04/27] add a version number to ram_list, Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 02/27] split MRU ram list, Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 06/27] ram: introduce migration_bitmap_set_dirty(), Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 05/27] protect the ramlist with a separate mutex, Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 03/27] savevm: Factorize ram globals reset in its own function, Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 08/27] ram: Export last_ram_offset(), Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 09/27] ram: introduce migration_bitmap_sync(), Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 12/27] buffered_file: rename opaque to migration_state, Juan Quintela, 2012/07/24
- [Qemu-devel] [PATCH 10/27] Separate migration bitmap, Juan Quintela, 2012/07/24