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aio_co_wake provides the infrastructure to start a coroutine on a "home" AioContext. It will be used by CoMutex and CoQueue, so that coroutines don't jump from one context to another when they go to sleep on a mutex or waitqueue. However, it can also be used as a more efficient alternative to one-shot bottom halves, and saves the effort of tracking which AioContext a coroutine is running on. aio_co_schedule is the part of aio_co_wake that starts a coroutine on a remove AioContext, but it is also useful to implement e.g. bdrv_set_aio_context callbacks. The implementation of aio_co_schedule is based on a lock-free multiple-producer, single-consumer queue. The multiple producers use cmpxchg to add to a LIFO stack. The consumer (a per-AioContext bottom half) grabs all items added so far, inverts the list to make it FIFO, and goes through it one item at a time until it's empty. The data structure was inspired by OSv, which uses it in the very code we'll "port" to QEMU for the thread-safe CoMutex. Most of the new code is really tests. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213135235.12274-3-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
26 lines
603 B
C
26 lines
603 B
C
/*
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* Event loop thread implementation for unit tests
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*
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* Copyright Red Hat Inc., 2013, 2016
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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* Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#ifndef TEST_IOTHREAD_H
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#define TEST_IOTHREAD_H
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#include "block/aio.h"
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#include "qemu/thread.h"
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typedef struct IOThread IOThread;
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IOThread *iothread_new(void);
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void iothread_join(IOThread *iothread);
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AioContext *iothread_get_aio_context(IOThread *iothread);
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#endif
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