On Sun, Mar 06, 2022 at 10:27:28PM +0200, Nir Soffer wrote:
> The aio_copy example checks errors properly, so it will not leak
> uninitialized memory to the destination image. Testing shows 5% speedup
> when copying a real image.
>
> $ qemu-nbd --read-only --persistent --shared 8 --cache none --aio native \
> --socket /tmp/src.sock --format raw fedora-35-data.raw &
>
> $ hyperfine -p "sleep 5" "./aio_copy-init $SRC >/dev/null"
> "./aio_copy-no-init $SRC >/dev/null"
>
> Benchmark 1: ./aio_copy-init nbd+unix:///?socket=/tmp/src.sock >/dev/null
> Time (mean ± σ): 1.452 s ± 0.027 s [User: 0.330 s, System: 0.489 s]
> Range (min … max): 1.426 s … 1.506 s 10 runs
>
> Benchmark 2: ./aio_copy-no-init nbd+unix:///?socket=/tmp/src.sock >/dev/null
> Time (mean ± σ): 1.378 s ± 0.009 s [User: 0.202 s, System: 0.484 s]
> Range (min … max): 1.369 s … 1.399 s 10 runs
>
> Summary
> './aio_copy-no-init nbd+unix:///?socket=/tmp/src.sock >/dev/null' ran
> 1.05 ± 0.02 times faster than './aio_copy-init
> nbd+unix:///?socket=/tmp/src.sock >/dev/null'
>
> Signed-off-by: Nir Soffer <[email protected]>
> ---
> golang/examples/aio_copy/aio_copy.go | 5 +++++
> golang/examples/simple_copy/simple_copy.go | 5 +++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/golang/examples/aio_copy/aio_copy.go
> b/golang/examples/aio_copy/aio_copy.go
> index bb20b478..89eac4df 100644
> --- a/golang/examples/aio_copy/aio_copy.go
> +++ b/golang/examples/aio_copy/aio_copy.go
> @@ -84,20 +84,25 @@ func main() {
> err = h.ConnectUri(flag.Arg(0))
> if err != nil {
> panic(err)
> }
>
> size, err := h.GetSize()
> if err != nil {
> panic(err)
> }
>
> + err = h.SetPreadInitialize(false)
> + if err != nil {
> + panic(err)
> + }
> +
In patch #2 you added a comment above the call.
Because this is an example and so people may just copy the code
blindly without understanding it, I think adding a comment here and
below is worth doing too.
> diff --git a/golang/examples/simple_copy/simple_copy.go
> b/golang/examples/simple_copy/simple_copy.go
> index e8fa1f76..2a2ed0ff 100644
> --- a/golang/examples/simple_copy/simple_copy.go
> +++ b/golang/examples/simple_copy/simple_copy.go
> @@ -63,20 +63,25 @@ func main() {
> err = h.ConnectUri(flag.Arg(0))
> if err != nil {
> panic(err)
> }
>
> size, err := h.GetSize()
> if err != nil {
> panic(err)
> }
>
> + err = h.SetPreadInitialize(false)
> + if err != nil {
> + panic(err)
> + }
> +
And above this one.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-p2v converts physical machines to virtual machines. Boot with a
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