On 05/24/2017 03:01 PM, Peter Xu wrote:
On Wed, May 24, 2017 at 10:56:37AM +0300, Alexey wrote:
On Wed, May 24, 2017 at 02:57:36PM +0800, Peter Xu wrote:
On Tue, May 23, 2017 at 02:31:08PM +0300, Alexey Perevalov wrote:
This patch adds ability to track down already copied
pages, it's necessary for calculation vCPU block time in
postcopy migration feature and maybe for restore after
postcopy migration failure.
Functions which work with RAMBlock are placed into ram.c,
due to TARGET_WORDS_BIGENDIAN is poisoned int postcopy-ram.c -
hardware independed code.
Signed-off-by: Alexey Perevalov <a.pereva...@samsung.com>
---
include/migration/migration.h | 16 +++++++++++
migration/postcopy-ram.c | 22 ++++++++++++---
migration/ram.c | 63 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 97 insertions(+), 4 deletions(-)
diff --git a/include/migration/migration.h b/include/migration/migration.h
index 449cb07..4e05c83 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -101,6 +101,20 @@ struct MigrationIncomingState {
LoadStateEntry_Head loadvm_handlers;
/*
+ * bitmap indicates whether page copied,
+ * based on ramblock offset
+ * now it is using only for blocktime calculation in
+ * postcopy migration, so livetime of this entry:
+ * since user requested blocktime calculation,
+ * till the end of postcopy migration
+ * as an example it could represend following memory map
+ * ___________________________________
+ * |4k pages | hugepages | 4k pages
Can we really do this?
The problem is AFAIU migration stream is sending pages only in target
page size, even for huge pages... so even for huge pages we should
still need per TARGET_PAGE_SIZE bitmap?
sending maybe, but copying to userfault fd is doing in hugepage size
Yes you are right. :)
in case of hugetlbfs memory backend.
(Please refer to ram_state_init() on init of RAMBlock.bmap)
I thought to use bitmap per ramblock, but I decided to not do it,
because of following reasons:
1. There is only 4k ramblocks, for such ramblock it's not
optimal
Could you explain what do you mean by "there is only 4k ramblocks"?
sorry, could be ramblocks with 4k size,
as example, your's qemu hmp info ramblock shows
Block Name PSize Offset Used Total
/objects/mem 2 MiB 0x0000000000000000
0x0000000020000000 0x0000000020000000
vga.vram 4 KiB 0x0000000020060000
0x0000000001000000 0x0000000001000000
/rom@etc/acpi/tables 4 KiB 0x0000000021130000
0x0000000000020000 0x0000000000200000
pc.bios 4 KiB 0x0000000020000000
0x0000000000040000 0x0000000000040000
0000:00:03.0/e1000.rom 4 KiB 0x0000000021070000
0x0000000000040000 0x0000000000040000
0000:00:04.0/e1000.rom 4 KiB 0x00000000210b0000
0x0000000000040000 0x0000000000040000
0000:00:05.0/e1000.rom 4 KiB 0x00000000210f0000
0x0000000000040000 0x0000000000040000
pc.rom 4 KiB 0x0000000020040000
0x0000000000020000 0x0000000000020000
0000:00:02.0/vga.rom 4 KiB 0x0000000021060000
0x0000000000010000 0x0000000000010000
/rom@etc/table-loader 4 KiB 0x0000000021330000
0x0000000000001000 0x0000000000001000
/rom@etc/acpi/rsdp 4 KiB 0x0000000021331000
0x0000000000001000 0x0000000000001000
/rom@etc/table-loader and /rom@etc/acpi/rsdp has only one 4K page.
2. copied pages bitmap - it's attribute of incoming migration,
but ramblock it's general structure, although bmap it's about
dirty pages of precopy migrations, hmm, but RAMBlock also
contains unsentmap and it's for postcopy.
I thought you mean that copied pages are specific fields for incoming
so not suitable for RAMBlock struct? But the last sentence seems to
not support that idea... Hmm... Actually it sounds like a good idea to
me to put it into RAMBlock (but I maybe wrong).
Thanks,
--
Best regards,
Alexey Perevalov
