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Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page
From: |
Peter Xu |
Subject: |
Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page |
Date: |
Thu, 25 May 2017 15:25:45 +0800 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Thu, May 25, 2017 at 09:28:57AM +0300, Alexey Perevalov wrote:
> On 05/25/2017 02:30 AM, Peter Xu wrote:
> >On Wed, May 24, 2017 at 03:16:23PM +0300, Alexey Perevalov wrote:
> >>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 <address@hidden>
> >>>>>>---
> >>>>>> 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
> >> /address@hidden/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
> >> /address@hidden/table-loader 4 KiB 0x0000000021330000
> >> 0x0000000000001000
> >>0x0000000000001000
> >> /address@hidden/acpi/rsdp 4 KiB 0x0000000021331000
> >> 0x0000000000001000
> >>0x0000000000001000
> >>
> >>/address@hidden/table-loader and /address@hidden/acpi/rsdp has only one 4K
> >>page.
> >I see. Thanks for explaining this.
> >
> >A 4k sized ramblock means the bitmap would be only one unsigned long
> >width (via bitmap_new(1)). I still don't see why it's not good... :-)
> >
> Ok, I'll take into account your comment, and I'll place copied
>
> bitmap into RAMBlock.
Or we can wait for further comments in case you'll do extra work. :-)
Just to mention that Dave won't be here until next week, so you may
need to wait for some days until he can provide some further input.
Thanks,
--
Peter Xu
- Re: [Qemu-devel] [PATCH V6 04/10] migration: split ufd_version_check onto receive/request features part, (continued)
Message not available
- [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Alexey Perevalov, 2017/05/23
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Peter Xu, 2017/05/24
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Alexey, 2017/05/24
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Peter Xu, 2017/05/24
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Alexey Perevalov, 2017/05/24
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Peter Xu, 2017/05/24
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Alexey Perevalov, 2017/05/25
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page,
Peter Xu <=
- Re: [Qemu-devel] [PATCH V6 07/10] migration: add bitmap for copied page, Dr. David Alan Gilbert, 2017/05/31
Message not available