Chapter 15: PEP Changes — db-mux Migration

What's Changing in PEP

Migrating from db-proxy to db-mux for:

• Session engine (session blob read/write)
• Sequence number allocator
• ID generators (TEID, SEID)
• Retransmission cache

Why Batching Doesn't Help in PEP

PEP's DB access pattern is fundamentally different from DP:

• Session is stored as one blob (single SET/GET) — already optimal
• Retransmission lookup happens BEFORE session processing — can't batch with session write
• Different sessions use different hash slots — can't MSET across sessions
• Fire-and-forget writes after session completion don't add to end-to-end latency

Benefit: Pure CPU Savings

Even without batching, switching to db-mux saves CPU (zero allocs vs 2-3 per command). For PEP this is less critical (PEP is easier to scale out) but still worthwhile.

Gerrit Changes

• PCPB-25616: Use dbmux for session engine and seqno allocator
• PCPB-25616: Use dbmux for session engine, id generators, TEID/SEID generators
• Use dbmux in db-id-generator instead of db-proxy (up-common)

Mark as Complete