On 12/2/24 13:02, Eelco Chaudron wrote:
>
>
> On 2 Dec 2024, at 12:49, Ilya Maximets wrote:
>
>> On 12/2/24 12:43, Eelco Chaudron wrote:
>>>
>>>
>>> On 2 Dec 2024, at 12:34, Ilya Maximets wrote:
>>>
>>>> On 11/29/24 15:45, Eelco Chaudron wrote:
>>
>> <snip>
>>
>>>>>
>>>>> Hi Ales,
>>>>>
>>>>> It took me a bit longer to figure out what was going on, but I found the
>>>>> issue. Your test case creates three DP flows. The first two flows uses
>>>>> the dp_hash()/hash() match/action, which is not offloadable, while the
>>>>> third flow is simple and offloadable.
>>>>>
>>>>> What happens next is that the first two flows are processed in the ovs
>>>>> kernel module. However, as the third recirculated flow is applied in TC,
>>>>> it still does not exist in the kernel DP. As a result, the packet is sent
>>>>> for upcall handling. This process repeats for every packet as the flow
>>>>> keeps being installed in TC.
>>>>>
>>>>> - [ovs]
>>>>> recirc_id(0),in_port(2),eth(),eth_type(0x0800),ipv4(dst=10.0.0.2,frag=no),
>>>>> packets:9, bytes:882, used:0.125s, actions:hash(l4(0)),recirc(0x3)
>>>>> - [ovs]
>>>>> recirc_id(0x3),dp_hash(0xa/0xf),in_port(2),eth(),eth_type(0x0800),ipv4(frag=no),
>>>>> packets:9, bytes:882, used:0.125s, actions:ct(commit),recirc(0x4)
>>>>> - [tc ] recirc_id(0x4),in_port(2),eth(),eth_type(0x0800),ipv4(frag=no),
>>>>> packets:0, bytes:0, used:never, actions:3
>>>>
>>>> Hmm, but if the flow is in TC, why it is not dumped back and revalidated?
>>>> It shouldn't matter if it has any traffic or not.
>>>
>>> Not sure I understand your comment. It’s revalidated and removed in the end
>>> (as no traffic is hitting this rule). But if traffic comes again, we
>>> install it in TC again, so the same problem repeats.
>>
>> The question is: if the flow is in TC, why it is not showing up in
>> the detrace output? If it's in TC, it means we have the ukey and
>> it must have been revalidated at least once.
>
> Ah, that part :) Yes, that got me puzzled too. But we do not populate the
> xcache if there has been no traffic for this flow (which makes sense):
No, no. The flow is always revaliadated when it is dumped for the first time,
regardless of the traffic:
if (!used) {
/* Always revalidate the first time a flow is dumped. */
return true;
}
Or is need_revalidate == false in this case?
>
> revalidate_ukey()
>
> 2475 }
> 2476 } else if (!push.n_packets || ukey->xcache
> 2477 || !populate_xcache(udpif, ukey, push.tcp_flags)) {
> 2478 result = UKEY_KEEP;
> 2479 }
>
> Why it is working, most of the time in my setup, is because an actual
> revalidation is happening, and then we do populate the cache independently of
> received packets (through revalidate_ukey__). Same function;
>
> 2462 if (need_revalidate) {
> 2463 if (should_revalidate(udpif, ukey, push.n_packets)) {
> 2464 if (!ukey->xcache) {
> 2465 ukey->xcache = xlate_cache_new();
> 2466 } else {
> 2467 xlate_cache_clear(ukey->xcache);
> 2468 }
> 2469 result = revalidate_ukey__(udpif, ukey, push.tcp_flags,
> 2470 odp_actions, recircs,
> ukey->xcache,
> 2471 del_reason);
> 2472 } else {
> 2473 /* Delete, since it is too expensive to revalidate. */
> 2474 *del_reason = FDR_TOO_EXPENSIVE;
> 2475 }
>
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