From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Mike Voytovich <mike@zermattsystems.com>
Cc: linux-kernel@vger.kernel.org
Subject: RE: termios VMIN and VTIME behavior
Date: Wed, 23 Nov 2005 11:15:27 +0000 [thread overview]
Message-ID: <1132744527.7268.5.camel@localhost.localdomain> (raw)
In-Reply-To: <64F9B87B6B770947A9F8391472E0321603A075B1@ehost011-8.exch011.intermedia.net>
On Maw, 2005-11-22 at 20:32 -0800, Mike Voytovich wrote:
> Please disregard - the user app was reading less than VMIN in the read()
> call, so I suppose the current behavior in that case would be correct
> (returning immediately with the number of bytes passed into read()
> rather than waiting for VMIN or VTIME to be met before returning).
>
> It doesn't appear that the behavior in this case is explicitly defined
> by POSIX, but it seems like a reasonable thing to do.
Its pretty well defined. It was designed to optimise block serial
operations (uucp and the like)
VMIN - number of bytes you expect this packet
VTIME - when to give up waiting
The form 0, VTIME also being used to do polling on old SYSV that lacked
select/poll
next prev parent reply other threads:[~2005-11-23 10:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-23 4:32 Mike Voytovich
2005-11-23 11:15 ` Alan Cox [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-11-23 2:18 Mike Voytovich
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