[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-block] [Qemu-devel] [PATCH RFC for-2.6 0/3] block: Add meta di
From: |
John Snow |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH RFC for-2.6 0/3] block: Add meta dirty bitmap for migration/persistence |
Date: |
Mon, 7 Dec 2015 18:47:08 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 12/07/2015 12:59 AM, Fam Zheng wrote:
> Vladimir,
>
> This is what I propose to implement meta bitmap. It's implemented in the
> HBitmap level to be more efficient, and the interface slightly varies too.
>
I missed it: What was wrong with Vladimir's approach / what are the
benefits of this approach?
> I'd like to use these operations to make dirty bitmap persistence more
> efficient too: unchanged dirty bits don't need to be flushed to disk. So I'm
> posting this as a separate series for a common base for both sides.
>
This is a reasonable use of the meta-bitmap strategy in general.
Keep in mind Vladimir's approach to Meta bitmaps used a different
granularity such that 1 physical bit implied 1 sector needed to be
re-transmitted.
A meta-bitmap that keeps track of disk flushes may require a different
granularity than one used for migration.
> Posting as RFC as 2.6 dev phase is just starting, we can still tweak the
> interface and/or implementation to fit the need.
>
> Fam Zheng (3):
> HBitmap: Introduce "meta" bitmap to track bit changes
> tests: Add test code for meta bitmap
> block: Support meta dirty bitmap
>
> block.c | 46 ++++++++++++++++++++++++++++++-
> block/mirror.c | 3 +-
> blockdev.c | 3 +-
> include/block/block.h | 11 ++++++++
> include/qemu/hbitmap.h | 7 +++++
> migration/block.c | 2 +-
> tests/test-hbitmap.c | 74
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> util/hbitmap.c | 22 +++++++++++++++
> 8 files changed, 164 insertions(+), 4 deletions(-)
>