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Re: [Qemu-devel] [PATCH] migration: Fix rate limiting issue on RDMA migr
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH] migration: Fix rate limiting issue on RDMA migration |
Date: |
Wed, 14 Mar 2018 20:19:30 +0000 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
* Lidong Chen (address@hidden) wrote:
> RDMA migration implement save_page function for QEMUFile, but
> ram_control_save_page do not increase bytes_xfer. So when doing
> RDMA migration, it will use whole bandwidth.
Hi,
Thanks for this,
> Signed-off-by: Lidong Chen <address@hidden>
> ---
> migration/qemu-file.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index 2ab2bf3..217609d 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -253,7 +253,7 @@ size_t ram_control_save_page(QEMUFile *f, ram_addr_t
> block_offset,
> if (f->hooks && f->hooks->save_page) {
> int ret = f->hooks->save_page(f, f->opaque, block_offset,
> offset, size, bytes_sent);
> -
> + f->bytes_xfer += size;
I'm a bit confused, because I know rdma.c calls acct_update_position()
and I'd always thought that was enough.
That calls qemu_update_position(...) which increases f->pos but not
f->bytes_xfer.
f_pos is used to calculate the 'transferred' value in
migration_update_counters and thus the current bandwidth and downtime -
but as you say, not the rate_limit.
So really, should this f->bytes_xfer += size go in
qemu_update_position ?
Juan: I'm not sure I know why we have both bytes_xfer and pos.
Dave
> if (ret != RAM_SAVE_CONTROL_DELAYED) {
> if (bytes_sent && *bytes_sent > 0) {
> qemu_update_position(f, *bytes_sent);
> --
> 1.8.3.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK