On 10/26/2015 10:11 PM, Jason Wang wrote:
>
>
> On 10/27/2015 01:52 AM, Ravi Kerur wrote:
>> Ported earlier patch from Jason Wang (dated 12/26/2014).
>>
>> This patch tries to reduce the number of MSIX irqs required for
>> virtio-net by sharing a MSIX irq for each TX/RX queue pair through
>> channels. If transport support channel, about half of the MSIX irqs
>> were reduced.
>>
>> Signed-off-by: Ravi Kerur <rke...@gmail.com>
>> ---
>> drivers/net/virtio_net.c | 29 ++++++++++++++++++++++++++++-
>> 1 file changed, 28 insertions(+), 1 deletion(-)
>
> Thanks for the patches. Some minor comments:
>
> - If there's no big changes of the code, better keep my sign-offs :)
Sorry for that. Will fix it in 'v2'
> - Rusty does not like the name "channels", so better rename it to
> "virtqueue groups"
> - Build bot reports some compiling issues, this need to be fixed in next
> version.
I saw build failure email, it was reported against 2nd patch. All 3 patches
need to be applied for successful build. Will look into it and fix any issues.
> - The order of patches in this series is reversed, pach 1/3 should be
> 3/3. And better to have a cover letter to describe the motivation and
> changes since last series. (You can do this through git format-patch
> --cover)
> - Michale's comment about unnecessary wakeup of tx queue needs to be
> addressed, otherwise, we may get unnecessary tx interrupts.
I am working on it, will take care of above comments as well in 'v2'
> - Some benchmarks is needed to make sure there's no performance regression.
>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index d8838ded..d705cce 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -72,6 +72,9 @@ struct send_queue {
>>
>> /* Name of the send queue: output.$index */
>> char name[40];
>> +
>> + /* Name of the channel, shared with irq. */
>> + char channel_name[40];
>> };
>>
>> /* Internal representation of a receive virtqueue */
>> @@ -1529,6 +1532,8 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
>> int ret = -ENOMEM;
>> int i, total_vqs;
>> const char **names;
>> + const char **channel_names;
>> + unsigned *channels;
>>
>> /* We expect 1 RX virtqueue followed by 1 TX virtqueue, followed by
>> * possible N-1 RX/TX queue pairs used in multiqueue mode, followed by
>> @@ -1548,6 +1553,17 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
>> if (!names)
>> goto err_names;
>>
>> + channel_names = kmalloc_array(vi->max_queue_pairs,
>> + sizeof(*channel_names),
>> + GFP_KERNEL);
>> + if (!channel_names)
>> + goto err_channel_names;
>> +
>> + channels = kmalloc_array(total_vqs, sizeof(*channels),
>> + GFP_KERNEL);
>> + if (!channels)
>> + goto err_channels;
>> +
>> /* Parameters for control virtqueue, if any */
>> if (vi->has_cvq) {
>> callbacks[total_vqs - 1] = NULL;
>> @@ -1562,10 +1578,15 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
>> sprintf(vi->sq[i].name, "output.%d", i);
>> names[rxq2vq(i)] = vi->rq[i].name;
>> names[txq2vq(i)] = vi->sq[i].name;
>> + sprintf(vi->sq[i].channel_name, "txrx.%d", i);
>> + channel_names[i] = vi->sq[i].channel_name;
>> + channels[rxq2vq(i)] = i;
>> + channels[txq2vq(i)] = i;
>> }
>>
>> ret = vi->vdev->config->find_vqs(vi->vdev, total_vqs, vqs, callbacks,
>> - names);
>> + names, channels, channel_names,
>> + vi->max_queue_pairs);
>> if (ret)
>> goto err_find;
>>
>> @@ -1580,6 +1601,8 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
>> vi->sq[i].vq = vqs[txq2vq(i)];
>> }
>>
>> + kfree(channels);
>> + kfree(channel_names);
>> kfree(names);
>> kfree(callbacks);
>> kfree(vqs);
>> @@ -1587,6 +1610,10 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
>> return 0;
>>
>> err_find:
>> + kfree(channels);
>> +err_channels:
>> + kfree(channel_names);
>> +err_channel_names:
>> kfree(names);
>> err_names:
>> kfree(callbacks);
>
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