mirror of https://github.com/xemu-project/xemu.git
linux aio: some comments
Add some notes about Linux AIO explaining why we don't use AIO in some situations. Signed-off-by: Frediano Ziglio <freddy77@gmail.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@ -236,6 +236,10 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
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}
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#ifdef CONFIG_LINUX_AIO
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/*
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* Currently Linux do AIO only for files opened with O_DIRECT
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* specified so check NOCACHE flag too
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*/
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if ((bdrv_flags & (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) ==
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(BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) {
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@ -181,6 +181,7 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
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case QEMU_AIO_READ:
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io_prep_preadv(iocbs, fd, qiov->iov, qiov->niov, offset);
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break;
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/* Currently Linux kernel does not support other operations */
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default:
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fprintf(stderr, "%s: invalid AIO request type 0x%x.\n",
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__func__, type);
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