From owner-freebsd-hackers  Wed May 15 11:44:25 2002
Delivered-To: freebsd-hackers@freebsd.org
Received: from pintail.mail.pas.earthlink.net (pintail.mail.pas.earthlink.net [207.217.120.122])
	by hub.freebsd.org (Postfix) with ESMTP id 47DCB37B406
	for <freebsd-hackers@freebsd.org>; Wed, 15 May 2002 11:44:22 -0700 (PDT)
Received: from pool0412.cvx21-bradley.dialup.earthlink.net ([209.179.193.157] helo=mindspring.com)
	by pintail.mail.pas.earthlink.net with esmtp (Exim 3.33 #2)
	id 1783kw-00060x-00; Wed, 15 May 2002 11:44:10 -0700
Message-ID: <3CE2AC5C.5B511B16@mindspring.com>
Date: Wed, 15 May 2002 11:43:40 -0700
From: Terry Lambert <tlambert2@mindspring.com>
X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony}  (Win98; U)
X-Accept-Language: en
MIME-Version: 1.0
To: Zhihui Zhang <zzhang@cs.binghamton.edu>
Cc: Doug White <dwhite@resnet.uoregon.edu>,
	freebsd-hackers@FreeBSD.ORG
Subject: Re: Collect process sleeping statistics
References: <Pine.SOL.4.21.0205151325290.17622-100000@onyx>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-hackers.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-hackers>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-hackers>
X-Loop: FreeBSD.ORG

Zhihui Zhang wrote:
> Basically I have a program that does a lot of I/O and alloctes/frees a lot
> of memory. The time command gives result like this:
> 
> 6.239u 19.329s 7:59.76 5.3%     310+775k 3993+246io 7pf+0w
> 
> I want to know why CPU is running only 5.3% of the total time. I just
> want know how long it is waiting for memory and how long it is waiting for
> I/O.  No other process is running at the same time.

You got 7 page faults with 0 waits.

So it was waiting for I/O 94.7% of the time.  That's statistical;
the real calculation is 100% - 246/3993 = 93.8%.

Generally, this comes down to a design issue that's very common
in code these days, particularly code where people think "threads
solve all concurrency problems".

I think I should patent the correct way of solving this problem,
since no one seems to use it.  I'll call it "interleaved I/O"...

-- Terry

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message