Re: [Libguestfs] [PATCH libnbd 4/9] golang: aio_buffer.go: Add MakeAioBufferZero()

On Sun, Jan 30, 2022 at 01:33:32AM +0200, Nir Soffer wrote: > Make it easy to create a zeroed buffer via calloc(), preventing leaking > sensitive info from the heap. > > Benchmarking show that creating a zeroed buffer is much slower compared shows

> with uninitialized buffer, but much faster compared with manually > initializing the buffer with a loop. > > BenchmarkMakeAioBuffer-12 7252674 148.1 ns/op > BenchmarkMakeAioBufferZero-12 262107 4181 ns/op > BenchmarkAioBufferZero-12 17581 68759 ns/op > > It is interesting that creating a zeroed buffer is 3 times faster > compared with making a new []byte slice: > > BenchmarkMakeAioBufferZero-12 247710 4440 ns/op > BenchmarkMakeByteSlice-12 84117 13733 ns/op Some of this is due to how much vectorization the standard library (whether libc or Go's core libraries) can do when bulk-zeroing (zeroing 64 bits, or even a cache line at a time, in an unrolled loop, is always going to be more performant than a naive loop of one byte at a time). > > Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt; > --- > golang/aio_buffer.go | 6 ++++++ > golang/libnbd_620_aio_buffer_test.go | 16 ++++++++++++++++ Another file that may fit better in the 0xx naming, especially if we decide to duplicate similar functionality into the python or OCaml bindings of being able to pre-generate a known-zero buffer for use in passing to nbd_pread. As a helper API, this seems useful. But do we need any man page documentation of a language-specific helper function?