GCP kTLS Results

Setup

• Platform: GCP c4-highcpu (Xeon Platinum 8581C)
• Region: europe-west4-a
• TLS: HD with kTLS, TS with Go crypto/tls
• Clients: 4 x c4-highcpu-8, 5 peers each
• Configs: 2, 4, 8, 16 vCPU

Summary

Config	HD Peak (Mbps)	HD Loss	TS Ceiling (Mbps)	TS Loss @ HD Peak	HD/TS
2 vCPU (1w)	3,730	1.65%	1,870	92%	10.8x
4 vCPU (2w)	6,091	1.97%	2,798	74%	3.5x
8 vCPU (4w)	12,316	0.68%	4,670	44%	2.7x
16 vCPU (8w)	16,545	1.51%	7,834	17%	2.1x

Rate Sweeps

2 vCPU (1 worker)

Rate	HD (Mbps)	+/-CI	HD Loss	TS (Mbps)	TS Loss	Ratio
1G	871	0	0.00%	870	0.00%	1.0x
2G	1,741	0	0.00%	1,718	1.36%	1.0x
3G	2,612	0	0.00%	1,870	28.28%	1.4x
5G	3,536	63	1.35%	324	92.43%	10.9x
7.5G	3,730	77	1.65%	347	92.34%	10.8x

At 2 vCPU TS collapses above 3G offered -- the Go runtime consumes the entire CPU budget. HD continues to deliver through backpressure.

4 vCPU (2 workers)

Rate	HD (Mbps)	+/-CI	HD Loss	TS (Mbps)	TS Loss	Ratio
3G	2,612	0	0.00%	2,518	3.33%	1.0x
5G	4,233	75	0.07%	2,798	35.58%	1.5x
7.5G	5,457	114	0.32%	1,605	73.90%	3.4x
10G	6,074	79	2.04%	1,738	73.13%	3.5x

8 vCPU (4 workers)

Rate	HD (Mbps)	+/-CI	HD Loss	TS (Mbps)	TS Loss	Ratio
5G	4,353	0	0.00%	4,291	1.26%	1.0x
7.5G	6,459	84	0.01%	4,670	28.36%	1.4x
10G	8,371	162	0.06%	4,495	44.13%	1.9x
15G	11,087	324	0.32%	4,482	43.83%	2.5x
20G	12,316	247	0.68%	4,488	43.81%	2.7x

16 vCPU (8 workers)

Rate	HD (Mbps)	+/-CI	HD Loss	TS (Mbps)	TS Loss	Ratio
7.5G	6,530	0	0.00%	6,368	2.33%	1.0x
10G	8,624	106	0.01%	7,510	13.62%	1.1x
15G	12,088	419	0.36%	7,799	16.79%	1.5x
20G	14,354	581	0.29%	7,810	16.62%	1.8x
25G	16,545	746	1.51%	7,834	16.43%	2.1x

Packet Loss

HD stays below 2% loss at peak. TS loss scales with offered rate -- 17% at 16 vCPU, 92% at 2 vCPU.

Scaling