Re: [Qemu-devel] [PATCH v5 11/12] qemu-io: adds support for io_uring

[Stefan Hajnoczi]

On Mon, Jun 10, 2019 at 07:19:04PM +0530, Aarushi Mehta wrote:
> Signed-off-by: Aarushi Mehta <address@hidden>
> ---
>  qemu-io.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/qemu-io.c b/qemu-io.c
> index 8d5d5911cb..54b82151c4 100644
> --- a/qemu-io.c
> +++ b/qemu-io.c
> @@ -129,6 +129,7 @@ static void open_help(void)
>  " -n, -- disable host cache, short for -t none\n"
>  " -U, -- force shared permissions\n"
>  " -k, -- use kernel AIO implementation (on Linux only)\n"
> +" -i  -- use kernel io_uring (Linux 5.1+)\n"
>  " -t, -- use the given cache mode for the image\n"
>  " -d, -- use the given discard mode for the image\n"
>  " -o, -- options to be given to the block driver"
> @@ -188,6 +189,11 @@ static int open_f(BlockBackend *blk, int argc, char 
> **argv)
>          case 'k':
>              flags |= BDRV_O_NATIVE_AIO;
>              break;
> +#ifdef CONFIG_LINUX_IO_URING
> +        case 'i':
> +            flags |= BDRV_O_IO_URING;
> +            break;
> +#endif
>          case 't':
>              if (bdrv_parse_cache_mode(optarg, &flags, &writethrough) < 0) {
>                  error_report("Invalid cache option: %s", optarg);
> @@ -290,6 +296,7 @@ static void usage(const char *name)
>  "  -C, --copy-on-read   enable copy-on-read\n"
>  "  -m, --misalign       misalign allocations for O_DIRECT\n"
>  "  -k, --native-aio     use kernel AIO implementation (on Linux only)\n"
> +"  -i  --io_uring       use kernel io_uring (Linux 5.1+)\n"
>  "  -t, --cache=MODE     use the given cache mode for the image\n"
>  "  -d, --discard=MODE   use the given discard mode for the image\n"
>  "  -T, --trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
> @@ -499,6 +506,7 @@ int main(int argc, char **argv)
>          { "copy-on-read", no_argument, NULL, 'C' },
>          { "misalign", no_argument, NULL, 'm' },
>          { "native-aio", no_argument, NULL, 'k' },
> +        { "io_uring", no_argument, NULL, 'i' },
>          { "discard", required_argument, NULL, 'd' },
>          { "cache", required_argument, NULL, 't' },
>          { "trace", required_argument, NULL, 'T' },
> @@ -566,6 +574,11 @@ int main(int argc, char **argv)
>          case 'k':
>              flags |= BDRV_O_NATIVE_AIO;
>              break;
> +#ifdef CONFIG_LINUX_IO_URING
> +        case 'i':
> +            flags |= BDRV_O_IO_URING;
> +            break;
> +#endif

An --aio=threads|native|io_uring option would be more general than
adding --io_uring.  That new AIO engines do not require their own
command-line options.

Can you implement something like the -drive aio= parameter so that a
single option can specify threads, native, or io_uring?

Thanks,
Stefan

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