[dpdk-dev] [PATCH v2 0/5] virtio: Tx performance improvements

Xie, Huawei huawei.xie at intel.com
Thu Oct 22 12:38:33 CEST 2015


On 10/21/2015 9:20 PM, Thomas Monjalon wrote:
> 2015-10-18 22:16, Stephen Hemminger:
>> This is a tested version of the virtio Tx performance improvements
>> that I posted earlier on the list, and described at the DPDK Userspace
>> meeting in Dublin. Together they get a 25% performance improvement for
>> both small packet and large multi-segment packet case when testing
>> from DPDK guest application to Linux KVM host.
>>
>> Stephen Hemminger (5):
>>   virtio: clean up space checks on xmit
>>   virtio: don't use unlikely for normal tx stuff
>>   virtio: use indirect ring elements
>>   virtio: use any layout on transmit
>>   virtio: optimize transmit enqueue
> Huawei, do you ack this series?
>
Okay with this patchset with two remained questions,

+/* Region reserved to allow for transmit header and indirect ring */
+#define VIRTIO_MAX_TX_INDIRECT 8
+struct virtio_tx_region {
+	struct virtio_net_hdr_mrg_rxbuf tx_hdr;

Why use merge-able rx header here in the tx region?

> +	struct vring_desc tx_indir[VIRTIO_MAX_TX_INDIRECT]
> +			   __attribute__((__aligned__(16)));

WARNING: __aligned(size) is preferred over __attribute__((aligned(size)))
[...]





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