On 04/23/2013 12:13 AM, Rusty Russell wrote:
> Sasha Levin <sasha.levin@xxxxxxxxxx> writes:
>> Due to MQ support we may allocate a whole bunch of rx queues but
>> never use them. With this patch we'll safe the space used by
>> the receive buffers until they are actually in use:
>
> Idea is good, implementation needs a tiny tweak:
>
>> @@ -912,8 +913,13 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
>> dev_warn(&dev->dev, "Fail to set num of queue pairs to %d\n",
>> queue_pairs);
>> return -EINVAL;
>> - } else
>> + } else {
>> + if (queue_pairs > vi->curr_queue_pairs)
>> + for (i = 0; i < queue_pairs; i++)
>> + if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
>> + schedule_delayed_work(&vi->refill, 0);
>> vi->curr_queue_pairs = queue_pairs;
>> + }
>>
>> return 0;
>> }
>
> You don't want to refill existing queues, so you don't need the "if".
>
> for (i = vi->curr_queue_pairs; i < queue_pairs; i++) {
> if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
> schedule_delayed_work(&vi->refill, 0);
That makes more sense, I'll resend.
> We don't free up buffers when we're reducing queues, but I consider that
> a corner case.
It didn't bother anyone up until now, and the spec doesn't state anything
about it - so I preferred to just leave that alone. Unless the ARM folks
would find it useful?
Thanks,
Sasha
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