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[Qemu-devel] [PATCH v7 0/4] Coroutines for better asynchronous programmi
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v7 0/4] Coroutines for better asynchronous programming |
Date: |
Mon, 25 Jul 2011 21:04:06 +0100 |
Here is the latest version of the coroutines series which both virtfs and the
block layer are now building on.
QEMU is event-driven and suffers when blocking operations are performed because
VM execution may be stopped until the operation completes. Therefore many
operations that could block are performed asynchronously and a callback is
invoked when the operation has completed. This allows QEMU to continue
executing while the operation is pending.
The downside to callbacks is that they split up code into many smaller
functions, each of which is a single step in a state machine that quickly
becomes complex and hard to understand. Callback functions also result in lots
of noise as variables are packed and unpacked into temporary structs that pass
state to the callback function.
This patch series introduces coroutines as a solution for writing asynchronous
code while still having a nice sequential control flow. The semantics are
explained in the second patch. The fourth patch adds automated tests.
A nice feature of coroutines is that it is relatively easy to take synchronous
code and lift it into a coroutine to make it asynchronous. Work has been done
to move qcow2 request processing into coroutines and thereby make it
asynchronous (today qcow2 will perform synchronous metadata accesses). This
qcow2 work is still ongoing and not quite ready for mainline yet.
v7:
* Reduce ucontext and win32 fiber stack size to 1 MB
* Add qemu-timer-common.o to test-coroutine dependencies for OpenBSD build
v6:
* Use GThread on Mac OS X, fix from Andreas Färber <address@hidden>
* abort(3) if coroutine-ucontext.c fails to create a coroutine
v5:
* GThread-based implementation for platforms without makecontext(3) (Aneesh
Kumar K.V <address@hidden>)
* Switch to gtester test framework
v4:
* Windows Fibers support (Paolo Bonzini <address@hidden>)
* Return-after-setjmp() fix (Aneesh Kumar K.V <address@hidden>)
* Re-entrancy for multi-threaded coroutines support
* qemu-coroutine.h cleanup and documentation
v3:
* Updated LGPL v2 license header to use web link
* Removed atexit(3) pool freeing
* Removed thread-local current/leader
* Documented thread-safety limitation
* Disabled trace events
v2:
* Added ./check-coroutine --lifecycle-benchmark for performance measurement
* Split pooling into a separate patch with performance justification
* Set maximum pool size to prevent holding onto too many free coroutines
* Added atexit(3) handler to free pool
* Coding style cleanups
Aneesh Kumar K.V (1):
coroutine: implement coroutines using gthread
Kevin Wolf (1):
coroutine: introduce coroutines
Stefan Hajnoczi (2):
coroutine: add test-coroutine automated tests
coroutine: add test-coroutine --benchmark-lifecycle
.gitignore | 1 +
Makefile | 3 +-
Makefile.objs | 11 +++
configure | 18 ++++
coroutine-gthread.c | 131 ++++++++++++++++++++++++++++
coroutine-ucontext.c | 230 ++++++++++++++++++++++++++++++++++++++++++++++++++
coroutine-win32.c | 92 ++++++++++++++++++++
qemu-coroutine-int.h | 48 +++++++++++
qemu-coroutine.c | 75 ++++++++++++++++
qemu-coroutine.h | 95 +++++++++++++++++++++
test-coroutine.c | 192 +++++++++++++++++++++++++++++++++++++++++
trace-events | 5 +
12 files changed, 900 insertions(+), 1 deletions(-)
create mode 100644 coroutine-gthread.c
create mode 100644 coroutine-ucontext.c
create mode 100644 coroutine-win32.c
create mode 100644 qemu-coroutine-int.h
create mode 100644 qemu-coroutine.c
create mode 100644 qemu-coroutine.h
create mode 100644 test-coroutine.c
--
1.7.5.4
- [Qemu-devel] [PATCH v7 0/4] Coroutines for better asynchronous programming,
Stefan Hajnoczi <=