Low-latency Key-Value Store for SSD

Question

We are working on a SSD-backed key-value solution with the following properties:

• Throughput: 10000 TPS; 50/50 puts/gets;
• Latency: 1ms average, 99.9th pe

Answer 1

This is kind-of a harebrained idea but it MIGHT work. Let's assume that your SSD is 128GB.

1. Create a 128GB swap partition on the SSD
2. Configure your machine to use that as swap
3. Setup memcached on the machine and set a 128GB memory limit
4. Benchmark

Will the kernel be able to page stuff in and out fast enough? No way to know. That depends more on your hardware than the kernel.

Poul-Henning Kamp does something very similar to this in Varnish by making the kernel keep track of things (virtual vs physical memory) for Varnish rather than making Varnish do it. https://www.varnish-cache.org/trac/wiki/ArchitectNotes