Federico Parola <fede.parola@xxxxxxxxxx> writes: > On 06/06/20 01:34, David Ahern wrote: >> On 6/4/20 7:30 AM, Federico Parola wrote: >>> Hello everybody, >>> I'm implementing a token bucket algorithm to apply rate limit to traffic and I need the timestamp of packets to update the bucket. To get this information I'm using the bpf_ktime_get_ns() helper but I've discovered it has a non negligible impact on performance. I've seen there is work in progress to make hardware timestamps available to XDP programs, but I don't know if this feature is already available. Is there a faster way to retrieve this information? >>> Thanks for your attention. >>> >> bpf_ktime_get_ns should be fairly light. What kind of performance loss >> are you seeing with it? > I've run some tests on a program forwarding packets between two > interfaces and applying rate limit: using the bpf_ktime_get_ns() I can > process up to 3.84 Mpps, if I replace the helper with a lookup on a map > containing the current timestamp updated in user space I go up to 4.48 > Mpps. Can you share more details on the platform you're running this on? I.e., CPU and chipset details, network driver, etc. -Toke
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