netty5/transport-native-epoll/src/main
Matteo Merli 3a96e7373b Added option to do busy-wait on epoll (#8267)
Motivation:

Add an option (through a SelectStrategy return code) to have the Netty event loop thread to do busy-wait on the epoll.

The reason for this change is to avoid the context switch cost that comes when the event loop thread is blocked on the epoll_wait() call.

On average, the context switch has a penalty of ~13usec.

This benefits both:

The latency when reading from a socket
Scheduling tasks to be executed on the event loop thread.
The tradeoff, when enabling this feature, is that the event loop thread will be using 100% cpu, even when inactive.

Modification:

Added SelectStrategy option to return BUSY_WAIT
Epoll loop will do a epoll_wait() with no timeout
Use pause instruction to hint to processor that we're in a busy loop
Result:

When enabled, minimizes impact of context switch in the critical path
2018-09-28 22:52:00 +02:00
..
c Added option to do busy-wait on epoll (#8267) 2018-09-28 22:52:00 +02:00
java/io/netty/channel/epoll Added option to do busy-wait on epoll (#8267) 2018-09-28 22:52:00 +02:00