iyzhang

8 ms·

1.
by iyzhang 7y ago
I consider POSIX to be high-level. The RDMA and DPDK interface are not.
2.
by iyzhang 7y ago
The Demikernel is not a unikernel. It is a library OS compiled as a series of shared libraries. It is not compiled together with the application and doesn’t take into account what features the application uses. It is designed to work with k
3.
by iyzhang 7y ago
Paper can be found here: http://irenezhang.net/papers/demikernel-hotos19.pdf
4.
by iyzhang 7y ago
It looks POSIX-like but uses high-level queues and fixes some issues with epoll. The lack of an atomic data unit and the overhead of the poor epoll interface cost too much to retain for kernel-bypass. Take a look at the paper for more deta
5.
by iyzhang 7y ago
BTW, the Demikernel will be open-sourced shortly .. as soon as I return from giving a talk at KubeCon Europe.
6.
by iyzhang 7y ago
It depends on the interface for the drivers to the application. However, UIO doesn't seem to support DMA, which is a non-starter. RDMA and DPDK both use user-space drivers, which is necessary for kernel-bypass. I'm not advocating
7.
by iyzhang 7y ago
I've updated the blog post with our experimental results from the Redis benchmark. Here is a link to the graph: http://irenezhang.net/img/demikernel-redis-exp.jpg
8.
by iyzhang 7y ago
High-level means not exposing hardware limitations to the application. The primary target applications are datacenter services, which spend much of their time processing network I/O. As network latencies lower to a few microseconds, da
9.
by iyzhang 10y ago
This implementation is an optimization of leader-based protocols like Raft. It removes the leader from the critical path using SDN.
10.
by iyzhang 11y ago
No, that was our key insight. Basically, you can think of it as, using something like Paxos requires all replicas to run the same code. So every replica checks for transaction conflicts. However, you actually only need one replica to detect
11.
by iyzhang 11y ago
Figure 14 in the paper gives comparisons with MongoDB, Redis and Cassandra using YCSB. The git repo has the YCSB bindings for TAPIR, so you can run TAPIR against any of the other systems that also have YCSB bindings.
12.
by iyzhang 11y ago
The leader bottleneck will continue to exist even if there great sharding because the leaders simply process more messages than the replicas, so TAPIR will allow each shard to support more throughput. The paper has an evaluation for multi-d
13.
TAPIR: A new high-performance, transactional key-value store(github.com)
134 points by iyzhang 11y ago|28 comments