On Wed, 22 Mar 2023 at 12:18, Jonathan Wakely wrote:

> On Wed, 22 Mar 2023 at 12:14, Jonathan Wakely wrote:
>
>>
>>
>> On Mon, 20 Mar 2023 at 22:30, Jonathan Wakely via Libstdc++ <
>> libstdc++@gcc.gnu.org> wrote:
>>
>>> On 20/03/23 22:27 +0000, Jonathan Wakely wrote:
>>> >On 06/03/23 20:52 +0100, Jannik Glückert wrote:
>>> >>we were previously only using sendfile for files smaller than 2GB, as
>>> >>sendfile needs to be called repeatedly for files bigger than that.
>>> >>
>>> >>some quick numbers, copying a 16GB file, average of 10 repetitions:
>>> >>   old:
>>> >>       real: 13.4s
>>> >>       user: 0.14s
>>> >>       sys : 7.43s
>>> >>   new:
>>> >>       real: 8.90s
>>> >>       user: 0.00s
>>> >>       sys : 3.68s
>>> >>
>>> >>Additionally, this fixes
>>> >>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108178
>>> >>
>>> >>libstdc++-v3/ChangeLog:
>>> >>
>>> >>       * acinclude.m4 (_GLIBCXX_HAVE_LSEEK): define
>>> >>       * config.h.in: Regenerate.
>>> >>       * configure: Regenerate.
>>> >>       * src/filesystem/ops-common.h: enable sendfile for files
>>> >>         >2GB in std::filesystem::copy_file, skip zero-length files
>>>
>>> Also, the ChangeLog entry needs to be indented with tabs, name the
>>> changed functions, and should be complete sentences, e.g.
>>>
>>>         * acinclude.m4 (_GLIBCXX_HAVE_LSEEK): Define.
>>>         * config.h.in: Regenerate.
>>>         * configure: Regenerate.
>>>         * src/filesystem/ops-common.h (copy_file_sendfile): Define new
>>>         function for sendfile logic. Loop to support large files. Skip
>>>         zero-length files.
>>>         (do_copy_file): Use it.
>>>
>>>
>> Here's what I plan to commit in a few weeks when GCC 14 Stage 1 opens.
>>
>>
>>
> And similarly for the copy_file_range change.
>

And finally, here's the fix for PR libstdc++/108178, replacing the
zero-size check with checking for EOF in the source file