Hi,
On 2021/3/9 5:36, Peter Xu wrote:
On Mon, Mar 08, 2021 at 09:58:02PM +0800, Kunkun Jiang wrote:
Hi,
On 2021/3/5 22:30, Peter Xu wrote:
On Fri, Mar 05, 2021 at 03:50:35PM +0800, Kunkun Jiang wrote:
Starting from pss->page, ram_save_host_page() will check every page
and send the dirty pages up to the end of the current host page or
the boundary of used_length of the block. If the host page size is
a huge page, the step "check" will take a lot of time.
This will improve performance to use migration_bitmap_find_dirty().
Is there any measurement done?
I tested it on Kunpeng 920. VM params: 1U 4G( page size 1G).
The time of ram_save_host_page() in the last round of ram saving:
before optimize: 9250us after optimize: 34us
Looks like an idle VM, but still this is a great improvement. Would you mind
add this into the commit message too?
Ok, I will add it in the next version.😉
This looks like an optimization, but to me it seems to have changed a lot
context that it doesn't need to... Do you think it'll also work to just look up
dirty again and update pss->page properly if migration_bitmap_clear_dirty()
returned zero?
Thanks,
This just inverted the body of the loop, suggested by @David Edmondson.
Here is the v2[1]. Do you mean to change it like this?
[1]:
http://patchwork.ozlabs.org/project/qemu-devel/patch/20210301082132.1107-4-jiangkun...@huawei.com/
I see, then it's okay - But indeed I still prefer your previous version. :)
Thanks,
Both versions are fine to me. This version may make the final code
slightly cleaner, I think.
Thanks,
Kunkun Jiang
