Project

General

Profile

Feature #13867

Copy offloading in IO.copy_stream

Added by Glass_saga (Masaki Matsushita) 18 days ago. Updated 18 days ago.

Status:
Open
Priority:
Normal
Assignee:
-
Target version:
[ruby-core:82646]

Description

In linux 4.5, the copy offloading feature with copy_file_range(2) was introduced.
This patch enables IO.copy_stream to use it.
If "offload" keyword argument is specified, IO.copy_stream will try copy offloading.

IO.copy_stream("src", "dst", offload: true)

If copy offloading is not available on the system, "offload" option will be ignored.

When "src" and "dst" are not in the same filesystem, copy_file_range(2) must fail with EXDEV.
In this case, IO.copy_steram will fallback to another method (sendfile(2) or read/write) silently.

It depends on the filesystem what offloading techniques will be used.
Copy offloading is optional in IO.copy_stream because some techniques may change the current behavior.

patch.diff (7.21 KB) patch.diff Glass_saga (Masaki Matsushita), 09/05/2017 09:06 AM

History

#1 [ruby-core:82652] Updated by normalperson (Eric Wong) 18 days ago

glass.saga@gmail.com wrote:

In linux 4.5, the copy offloading feature with copy_file_range(2) was introduced.
This patch enables IO.copy_stream to use it.

Cool.

If "offload" keyword argument is specified, IO.copy_stream will try copy offloading.

Is a new keyword arg necessary? Since this is Linux-only, and
we already do fstat tests on both FDs in the sendfile checking:

We can try using copy_file_range if both src and dst are both
regular files with identical .st_dev, and fall back to using
sendfile on ENOSYS.

Thanks.

Also available in: Atom PDF