DrTM's Concurrency Control Local tx vs local tx HTM Distributed tx vs distributed tx: 2PL Local x vs distributed tx: abort local Ix M1 M2 D-TX prior to L-TX RDMA op will abort local Ix RDMA (strong consistency him (strong atomicity 6
16 DrTM’s Concurrency Control Local TX vs. Local TX: HTM Distributed TX vs. Distributed TX: 2PL Local TX vs. Distributed TX: abort local TX RDMA (strong consistency) + HTM (strong atomicity) RDMA op will abort local TX D-TX prior to L-TX
DrTM's Concurrency Control Local tx vs local tx HTM Distributed tx vs distributed tx: 2PL Local x vs distributed tx: abort local Ix M1 M2 D-TX prior to L-TX Local accesses need check the state of records 7
17 DrTM’s Concurrency Control Local TX vs. Local TX: HTM Distributed TX vs. Distributed TX: 2PL Local TX vs. Distributed TX: abort local TX D-TX prior to L-TX Local accesses need check the state of records
Challenge# 2: Limit of RDMA Semantics RDMA provides three communication options o IPolB, SEND/RECV and one-sided RDMA ops Good performance(e.g latency and without involving the host CPU One-sided rdma has much limited interfaces 口READ,WRTE, CAS anoⅩADD How to support exclusive and shared accesses in 2PL protocol using one-sided RDMA ops 8
RDMA provides three communication options □ IPoIB, SEND/RECV and one-sided RDMA ops 18 Challenge#2: Limit of RDMA Semantics One-sided RDMA has much limited interfaces □ READ, WRITE, CAS and XADD Good performance (e.g. latency) and without involving the host CPU How to support exclusive and shared accesses in 2PL protocol using one-sided RDMA ops
DrTM’ s LOCk RDMA CAS: atomic compare-and-swap o Similar to the semantic of normal cas (i.e. local CAS 1. Drtm's exclusive lock Spinlock: use RDMA CAs to acquire release 2.DrM’ s shared lock Lease-based protocol 9
RDMA CAS: atomic compare-and-swap □ Similar to the semantic of normal CAS (i.e. local CAS) 1. DrTM’s exclusive lock − Spinlock: use RDMA CAS to acquire & release 2. DrTM’s shared lock − Lease-based protocol 19 DrTM’s Lock
Shared (read)Lock Lease-based protocol a Grant read right to the lock holder in a time period a No need to explicit release or invalidate the lock exclusive shared lock State Lease's end-time machine-ID exclusive-bit 000...0002 unlocked State is atomically compare 000... yYl2 exclusive locked and swap using RDMA Cas xxx.000 shared locked I Machine id is only used by recovery 20
Lease-based protocol □ Grant read right to the lock holder in a time period □ No need to explicit release or invalidate the lock 20 Shared (Read) Lock 55 1 exclusive & shared lock 8 Lease’s end-time machine-ID1 exclusive-bit State: 000...yy12 exclusive locked 000...0002 unlocked xxx...0002 shared locked State is atomically compare and swap usingRDMA CAS 1 Machine ID is only used by recovery