diff options
Diffstat (limited to 'src/lib/thread')
| -rw-r--r-- | src/lib/thread/lib_thread.md (renamed from src/lib/thread/lib_thread.dox) | 2 | ||||
| -rw-r--r-- | src/lib/thread/threading.md | 26 |
2 files changed, 26 insertions, 2 deletions
diff --git a/src/lib/thread/lib_thread.dox b/src/lib/thread/lib_thread.md index 2773aa009d..5870ad790f 100644 --- a/src/lib/thread/lib_thread.dox +++ b/src/lib/thread/lib_thread.md @@ -1,4 +1,3 @@ -/** @dir /lib/thread @brief lib/thread: Mid-level threading. @@ -6,4 +5,3 @@ This module contains compatibility and convenience code for multithreading, except for low-level locks (which are in \refdir{lib/lock} and workqueue/threadpool code (which belongs in \refdir{lib/evloop}.) -**/ diff --git a/src/lib/thread/threading.md b/src/lib/thread/threading.md new file mode 100644 index 0000000000..a1058c97de --- /dev/null +++ b/src/lib/thread/threading.md @@ -0,0 +1,26 @@ + +@page threading Threading in Tor + +Tor is based around a single main thread and one or more worker +threads. We aim (with middling success) to use worker threads for +CPU-intensive activities and the main thread for our networking. +Fortunately (?) we have enough cryptography that moving what we can +of the cryptographic processes to the workers should achieve good +parallelism under most loads. Unfortunately, we only have a small +fraction of our cryptography done in our worker threads right now. + +Our threads-and-workers abstraction is defined in workqueue.c, which +combines a work queue with a thread pool, and integrates the +signalling with libevent. Tor's main instance of a work queue is +instantiated in cpuworker.c. It will probably need some refactoring +as more types of work are added. + +On a lower level, we provide locks with tor_mutex_t in \refdir{lib/lock}, and +higher-level locking/threading tools in \refdir{lib/thread}, including +conditions (tor_cond_t), thread-local storage (tor_threadlocal_t), and more. + + +Try to minimize sharing between threads: it is usually best to simply +make the worker "own" all the data it needs while the work is in +progress, and to give up ownership when it's complete. + |