Check out my first novel, midnight's simulacra!
Fast UNIX Servers: Difference between revisions
From dankwiki
No edit summary |
|||
| Line 14: | Line 14: | ||
* [[epoll]] on [[Linux APIs|Linux]], <tt>/dev/poll</tt> on Solaris, [[kqueue]] on [[FreeBSD APIs|FreeBSD]] | * [[epoll]] on [[Linux APIs|Linux]], <tt>/dev/poll</tt> on Solaris, [[kqueue]] on [[FreeBSD APIs|FreeBSD]] | ||
* [http://liboop.ofb.net/ liboop], [http://software.schmorp.de/pkg/libev.html libev] and [http://www.monkey.org/~provos/libevent/ libevent] | * [http://liboop.ofb.net/ liboop], [http://software.schmorp.de/pkg/libev.html libev] and [http://www.monkey.org/~provos/libevent/ libevent] | ||
===Edge and Level Triggering=== | |||
* Historic interfaces like POSIX.1g/POSIX.1-2001's <tt>select(2)</tt> and POSIX.1-2001's <tt>poll(2)</tt> were level-triggered | |||
* <tt>epoll</tt> (via <tt>EPOLLET</tt>) and <tt>kqueue</tt> (via <tt>EV_CLEAR</tt>) provide edge-triggered semantics | |||
== | ==The Full Monty: A Theory of UNIX Servers== | ||
We must mix and match: | We must mix and match: | ||
* Many event sources, of multiple types and possibly various triggering mechanisms (edge- vs level-triggered): | * Many event sources, of multiple types and possibly various triggering mechanisms (edge- vs level-triggered): | ||
Revision as of 02:07, 25 June 2009
Everyone ought start with Dan Kegel's classic site, "The C10K Problem" (still updated from time to time). Jeff Darcy's "High-Performance Server Architecture" is much of the same. Everything here is advanced followup material to these excellent works, and of course the books of W. Richard Stevens.
- "sendfile(): fairly sexy (nothing to do with ECN)" on lkml
- "mmap() sendfile()" on freebsd-hackers
- "sharing memory map between processes (same parent)" on comp.unix.programmer
- "some mmap observations compared to Linux 2.6/OpenBSD" on freebsd-hackers
- Stuart Cheshire's "Laws of Networkdynamics" and "It's the Latency, Stupid"
Queueing Theory
- "Introduction to Queueing"
- Leonard Kleinrock's peerless two-volume Queueing Systems
Event Cores
Edge and Level Triggering
- Historic interfaces like POSIX.1g/POSIX.1-2001's select(2) and POSIX.1-2001's poll(2) were level-triggered
- epoll (via EPOLLET) and kqueue (via EV_CLEAR) provide edge-triggered semantics
The Full Monty: A Theory of UNIX Servers
We must mix and match:
- Many event sources, of multiple types and possibly various triggering mechanisms (edge- vs level-triggered):
- Socket descriptors, pipes
- File descriptors referring to actual files (these usually have different blocking semantics)
- Signals, perhaps being used for asynchronous I/O with descriptors (signalfd(2) on Linux unifies these with socket descriptors; kqueue supports EVFILT_SIGNAL events)
- Timers (timerfd(2) on Linux unifies these with socket descriptors; kqueue supports EVFILT_TIMER events)
- Condition variables becoming available
- Filesystem events (inotify(7) on Linux, EVFILT_VNODE with kqueue)
- Networking events (netlink(7) (PF_NETLINK) sockets on Linux, EVFILT_NETDEV with kqueue)
- One or more event notifiers (epoll or kqueue fd)
- One or more event vectors, into which notifiers dump events
- kqueue supports vectorized registration of event changes, extending the issue
- Threads
