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path: root/coroutine-ucontext.c
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2012-07-31configure: Split valgrind test into pragma test and valgrind.h testPeter Maydell1-0/+4
Split the configure test that checks for valgrind into two, one part checking whether we have the gcc pragma to disable unused-but-set variables, and the other part checking for the existence of valgrind.h. The first of these has to be compiled with -Werror and the second does not and shouldn't generate any warnings. This (a) allows us to enable "make errors in configure tests be build failures" and (b) enables use of valgrind on systems with a gcc which doesn't know about -Wunused-but-set-varibale, like Debian squeeze. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-07-17coroutine-ucontext: Help valgrind understand coroutinesKevin Wolf1-0/+28
valgrind tends to get confused and report false positives when you switch stacks and don't tell it about it. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
2012-02-17coroutine: switch to QSLISTPaolo Bonzini1-5/+5
QSLIST can be used for a free list, do it. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-12-15coroutine: switch per-thread free pool to a global poolAvi Kivity1-14/+16
ucontext-based coroutines use a free pool to reduce allocations and deallocations of coroutine objects. The pool is per-thread, presumably to improve locality. However, as coroutines are usually allocated in a vcpu thread and freed in the I/O thread, the pool accounting gets screwed up and we end allocating and freeing a coroutine for every I/O request. This is expensive since large objects are allocated via the kernel, and are not cached by the C runtime. Fix by switching to a global pool. This is safe since we're protected by the global mutex. Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-08-20Use glib memory allocation and free functionsAnthony Liguori1-8/+8
qemu_malloc/qemu_free no longer exist after this commit. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-08-08Unbreak the build on ppc32malc1-1/+1
Signed-off-by: malc <av1474@comtv.ru>
2011-08-01coroutine: introduce coroutinesKevin Wolf1-0/+230
Asynchronous code is becoming very complex. At the same time synchronous code is growing because it is convenient to write. Sometimes duplicate code paths are even added, one synchronous and the other asynchronous. This patch introduces coroutines which allow code that looks synchronous but is asynchronous under the covers. A coroutine has its own stack and is therefore able to preserve state across blocking operations, which traditionally require callback functions and manual marshalling of parameters. Creating and starting a coroutine is easy: coroutine = qemu_coroutine_create(my_coroutine); qemu_coroutine_enter(coroutine, my_data); The coroutine then executes until it returns or yields: void coroutine_fn my_coroutine(void *opaque) { MyData *my_data = opaque; /* do some work */ qemu_coroutine_yield(); /* do some more work */ } Yielding switches control back to the caller of qemu_coroutine_enter(). This is typically used to switch back to the main thread's event loop after issuing an asynchronous I/O request. The request callback will then invoke qemu_coroutine_enter() once more to switch back to the coroutine. Note that if coroutines are used only from threads which hold the global mutex they will never execute concurrently. This makes programming with coroutines easier than with threads. Race conditions cannot occur since only one coroutine may be active at any time. Other coroutines can only run across yield. This coroutines implementation is based on the gtk-vnc implementation written by Anthony Liguori <anthony@codemonkey.ws> but it has been significantly rewritten by Kevin Wolf <kwolf@redhat.com> to use setjmp()/longjmp() instead of the more expensive swapcontext() and by Paolo Bonzini <pbonzini@redhat.com> for Windows Fibers support. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>