How to pare down AWS Lambda costs by 50% or more
TLDR; Use BareMetal OS instead of AWS Linux (the standard Amazon Linux 2/2023 used in Lambda) to shift cost-effectiveness from cloud convenience to "hardware efficiency".
BareMetal OS is not just another Linux distribution; it is a 64-bit exokernel written entirely in x86-64 Assembly. This fundamental architectural difference is what drives its cost advantages.
1. Eliminating the "Instruction Tax"
Standard AWS Linux is built on C and designed for general-purpose multitasking. BareMetal OS is written in Assembly to be as lean as possible.
Minimal Footprint: The BareMetal OS kernel is roughly 16 KiB to 32 KiB. In contrast, a stripped-down Linux kernel (JeOS) is typically several megabytes.
Memory Efficiency: BareMetal OS consumes only about 2-4 MiB of RAM total. In an AWS Lambda environment, even the smallest 128MB function loses a significant chunk of its "billable" memory just to the overhead of the Linux runtime and background agents. With BareMetal OS, nearly 100% of the provisioned RAM is available for your application code.
2. No Context Switching (Zero Overhead)
In AWS Linux, the CPU constantly switches between "Kernel Mode" and "User Mode" to handle security and multitasking. This "context switching" consumes CPU cycles that you are paying for but not using for your code.
Single Address Space: BareMetal OS uses a Single Address Space Operating System (SASOS) model. It runs everything in Ring 0 (the highest privilege level).
The Savings: Because there is no overhead for context switching or moving data across kernel-user boundaries, a function running on BareMetal OS finishes faster than the same logic on AWS Linux. Since Lambda-style billing is per-millisecond, finishing 20% faster means a 20% direct reduction in cost.
3. "Just Enough OS" (JeOS) vs. Bloatware
AWS Linux comes pre-loaded with systemd, logging daemons, SSH servers, and package managers. Even if you don't use them, they consume CPU cycles and memory.
Mono-tasking for Performance: BareMetal OS is designed to "do one thing well." It uses an internal work queue that all CPU cores poll. A task executes until completion without being interrupted by the OS for other background tasks.
Deterministic Billing: On AWS Linux, "noisy neighbors" or background system updates can cause execution jitter. BareMetal OS provides deterministic performance, ensuring you never pay for "spikes" caused by the OS itself.
4. Avoiding the Virtualization Layer
AWS Lambda runs on Firecracker microVMs. While efficient, there is still a translation layer between your code and the physical silicon.
Direct Hardware Access: BareMetal OS acts as a thin hardware abstraction layer. If you run it on a Bare Metal server (like those from Equinix or OVH), your code interacts with the CPU and NIC with zero virtualization overhead.
Cost Scaling: For high-volume workloads, the cost of an AWS Lambda "managed fee" (roughly a 15-30% markup over raw EC2) can be eliminated by running a cluster of Bare Metal servers with Return Infinity's kernel.
Comparison Summary
| Feature | AWS Linux (Lambda/EC2) | BareMetal OS (Return Infinity) |
| Language | C / High-level | 100% Assembly |
| Kernel Size | ~5MB+ | ~16KB |
| Boot Time | Seconds (VM) / Milliseconds (Lambda) | Sub-millisecond |
| Overhead | Context switches & Background tasks | Zero (Mono-tasking) |
| Memory Usage | High (System overhead) | Extremely Low (~4MB total) |
| Cost Basis | Managed service premium | Raw hardware performance |
Conclusion: Why it is more cost-effective
Running Lambda-style "functions" on BareMetal OS is more cost-effective because it maximizes the "Work-per-Clock-Cycle." You aren't paying for a kernel to manage thousands of users; you are paying for a kernel that stays out of the way. For specialized, high-throughput tasks (like encryption, media transcoding, or high-frequency trading), BareMetal OS allows you to get 2x to 5x the performance out of the same physical hardware compared to a virtualized Linux environment.