Re: read() MAX_IO_SIZE bytes, more than SSIZE_MAX?

Randall S. Becker <rsbecker <at> nexbridge.com> writes:

On 2015-02-07 13:07PM Randall S. Becker wrote:

quoted

On 2015-02-07 12:30PM Torsten Bögershausen wrote:

quoted

On 2015-02-07 17.45, Joachim Schmitz wrote:

<spip> 

Although I do agree with Jojo, that MAX_IO_SIZE seems to be a platform
constant and should be defined in terms of SSIZE_MAX. So something like:

#ifndef MAX_IO_SIZE
# ifdef SSIZE_MAX
#  define MAX_IO_SIZE (SSIZE_MAX)
# else
#  define MAX_IO_SIZE (8*1024*1024)
# endif
#endif

would be desirable.

It would be way too large on some platforms. those 8MB had been chosen for 
a good reason, I assume:

/*
 * Limit size of IO chunks, because huge chunks only cause pain.  OS X
 * 64-bit is buggy, returning EINVAL if len >= INT_MAX; and even in
 * the absence of bugs, large chunks can result in bad latencies when
 * you decide to kill the process.
 */

However it should never be larger than SSIZE_MAX