Re: [EXT] Re: [PATCH v3] app/mldev: add internal function for file read

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

On Wed, May 03, 2023 at 11:28:26AM -0700, Stephen Hemminger wrote:
> On Wed, 3 May 2023 14:59:40 +0000
> Srikanth Yalavarthi <syalavarthi@marvell.com> wrote:
> 
> > > 
> > > Granted this is a test program. But why did you ignore my feedback that this
> > > is the slowest way to read a file. Stdio requires extra buffering, use regular
> > > read() or better yet mmap().  
> > 
> > Agree on the improvement, but, considering that this is a test code and these operations are done in slow-path, I would prefer to have the implementation based on C library calls rather than using system calls.
> > 
> > Also, using system calls may not make this code portable? Though we are not supporting this app on platforms other than Linux, as of now.
> > Pls let me know what you think.
> > 
> > I had shared my additional comments on v2 patch.
> 
> Using system calls read/write is used lots of places in DPDK already and is portable
> to all the supported platforms.

well almost, the windows standard c library implements a subset of
POSIX.1 (ISO/IEC 9945-1:1996) and there should be a strong emphasis on
`a subset' as in it is not fully conformant to any specific POSIX standard.

also because they aren't technically part of the standard C library
(again POSIX is not standard C) they are exposed with different names on
windows by prepending a leading `_' to the names. so you get `_read' instead
of `read' for example.

you can force exposure of the non-conforming names (i.e. the POSIX
names) with the _CRT_DECLARE_NONSTDC_NAMES define but if you do and you use
them you may then get deprecation warnings.

anyway, i read above nobody cares if this code ever runs on anything but
Linux ~forever so i won't make it my business to comment further unless
there is a desire to include windows.