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Re: [PATCH v4 1/2] migration/ram: Reduce unnecessary rate limiting
From: |
Peter Xu |
Subject: |
Re: [PATCH v4 1/2] migration/ram: Reduce unnecessary rate limiting |
Date: |
Tue, 16 Mar 2021 17:39:06 -0400 |
On Tue, Mar 16, 2021 at 08:57:15PM +0800, Kunkun Jiang wrote:
> When the host page is a huge page and something is sent in the
> current iteration, migration_rate_limit() should be executed.
> If not, it can be omitted.
>
> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
> Reviewed-by: David Edmondson <david.edmondson@oracle.com>
> ---
> migration/ram.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 72143da0ac..3eb5b0d7a7 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -2015,8 +2015,13 @@ static int ram_save_host_page(RAMState *rs,
> PageSearchStatus *pss,
>
> pages += tmppages;
> pss->page++;
> - /* Allow rate limiting to happen in the middle of huge pages */
> - migration_rate_limit();
> + /*
> + * Allow rate limiting to happen in the middle of huge pages if
> + * something is sent in the current iteration.
> + */
> + if (pagesize_bits > 1 && tmppages > 0) {
> + migration_rate_limit();
> + }
Sorry I'm still not a fan of this - I'd even prefer calling that once more just
to make sure it won't be forgotten to be called.. Not to say it's merely a
noop.
I'll leave this to Dave.. Maybe I'm too harsh! :)
--
Peter Xu