Messages in this thread | | | Date | Sun, 24 Nov 2013 00:22:54 +0000 | From | One Thousand Gnomes <> | Subject | Re: [PATCH tty-next 5/7] n_tty: Refactor input_available_p() by call site |
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On Fri, 22 Nov 2013 10:59:23 -0500 Peter Hurley <peter@hurleysoftware.com> wrote:
> Distinguish if caller is n_tty_poll() or n_tty_read(), and > set the read/wakeup threshold accordingly.
That looks very wrong to me. The poll() and read() wakeup should always match. In addition if MIN_CHAR is set without a timeout then it should not wake up until MIN_CHAR characters are present. The MIN_CHAR feature is used by various (these days obscure) protocols to optimise block transfer rates.
Changing this is also a userspace visible API change.
So NAK.
The underlying intention of the system (and SYS5.4) is that you can do
MIN_CHAR = 64
alarm(some_timeout) while(1) { poll(); events read(chunksized blocks) }
while it's hardly as critical with modern fast hardware its still the API and necessary to avoid SWS type behaviours in the queue turning it from block/syscall to byte I/O.
Alan
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