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From: "Carlos Fernández Sanz" <cfs-lk@fulanito.nisupu.com>
To: "Ignacio Vazquez-Abrams" <ignacio@openservices.net>,
	"Carlos Fernández Sanz" <cfs-lk@fulanito.nisupu.com>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: Fw: select(), EOF...
Date: Mon, 20 Aug 2001 23:09:53 +0200	[thread overview]
Message-ID: <009501c129bc$75724ca0$0414a8c0@10> (raw)
In-Reply-To: <Pine.LNX.4.33.0108201659080.11734-100000@terbidium.openservices.net>

a strace shows it works differently

nanosleep({1, 0}, {1, 0})               = 0
fstat(3, {st_mode=S_IFREG|0600, st_size=227128, ...}) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [RT_0], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [RT_0], NULL, 8) = 0

the file is opened just once (as I expected), and tail sleeps in nanosleep
() until the file grows. I think strace isn't showing more nanosleep() as it
should be looping there. BTW what's the reason for the sigprocmask, etc?

----- Original Message -----
From: "Ignacio Vazquez-Abrams" <ignacio@openservices.net>
To: "Carlos Fernández Sanz" <cfs-lk@fulanito.nisupu.com>
Cc: <linux-kernel@vger.kernel.org>
Sent: Monday, August 20, 2001 11:00 PM
Subject: Re: Fw: select(), EOF...


> On Mon, 20 Aug 2001, Carlos Fernández Sanz wrote:
>
> > How come the process is never runnable unless there's new data in the
file?
> > If it was opening and closing the file continously it would be using
lots of
> > CPU, while it's 0 if there's no data coming.
>
> It sleep()s between close() and open().
>
> --
> Ignacio Vazquez-Abrams  <ignacio@openservices.net>
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>


  reply	other threads:[~2001-08-20 21:11 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-08-20 20:38 Fw: select(), EOF Carlos Fernández Sanz
2001-08-20 20:45 ` Ignacio Vazquez-Abrams
2001-08-20 20:56   ` Carlos Fernández Sanz
2001-08-20 21:00     ` Ignacio Vazquez-Abrams
2001-08-20 21:09       ` Carlos Fernández Sanz [this message]
2001-08-20 21:29         ` Ignacio Vazquez-Abrams

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