Re: [PATCH v4 1/2] migration/ram: Reduce unnecessary rate limiting

[Kunkun Jiang <jiangkunkun@huawei.com>]

Hi  Peter,

On 2021/3/17 5:39, Peter Xu wrote:
> 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! :)
>
You are very serious and meticulous. I like your character very much.😉
This patch was used to reviewed by David. So, I want to know what
his opinion is.

@David
Hi David, what is your opinion on this patch?

Thanks,
Kunkun Jiang