Re: [dpdk-dev] [PATCH 1/3] examples/flow_classify: fix check of port and core

["Min Hu (Connor)" <humin29@huawei.com>]

在 2021/4/20 9:08, Thomas Monjalon 写道:
> 27/03/2021 08:40, Min Hu (Connor):
>> fix check of port and core in flow_classify example.
>>
>> Fixes: bab16ddaf2c1 ("examples/flow_classify: add sample application")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
>> ---
>>   	RTE_ETH_FOREACH_DEV(port)
>> -		if (rte_eth_dev_socket_id(port) > 0 &&
>> +		if (rte_eth_dev_socket_id(port) >= 0 &&
>>   			rte_eth_dev_socket_id(port) != (int)rte_socket_id()) {
>>   			printf("\n\n");
>>   			printf("WARNING: port %u is on remote NUMA node\n",
> 
> Please explain which case is broken and why.
> If I understand well, we don't detect remote NUMA if not running on first socket.
> 
Hi, the code is this:
*************************************************************************
	/*
	 * Check that the port is on the same NUMA node as the polling thread
	 * for best performance.
	 */
	RTE_ETH_FOREACH_DEV(port)
		if (rte_eth_dev_socket_id(port) > 0 &&
			rte_eth_dev_socket_id(port) != (int)rte_socket_id()) {
			printf("\n\n");
			printf("WARNING: port %u is on remote NUMA node\n",
			       port);
			printf("to polling thread.\n");
			printf("Performance will not be optimal.\n");
		}
	printf("\nCore %u forwarding packets. ", rte_lcore_id());
	printf("[Ctrl+C to quit]\n");
*************************************************************************

According to the comments and logging, the author just hope user to use
the core and device which are in the same numa node for optimal
performance. If not, A warning gives out.

For example in flow_classify:
./build/flow_classify -w 0000:7d:00.1  -l 93
Here:
0000:7d:00.1 is on numa node 0.
core 93  is on numa node 3.

the two are not in same numa node, but no warning gives out in old codes.

Well, using this patch, we can get the waring.

Thanks, Thomas.




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