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From: Han Pingtian <hanpt@linux.vnet.ibm.com>
To: ltp-list@lists.sourceforge.net
Subject: Re: [LTP] questions about getrusage04
Date: Mon, 8 Dec 2014 21:03:01 +0800	[thread overview]
Message-ID: <20141208130301.GB3352@localhost.localdomain> (raw)
In-Reply-To: <20141208120922.GD11071@rei.suse.de>

On Mon, Dec 08, 2014 at 01:09:22PM +0100, Cyril Hrubis wrote:
> Hi!
> > I cannot understand why udelta/sdelta > "1000+(BIAS_MAX*factor_nr)" is a
> > problem. Could any expert give me a explain, please?
> 
> It tests timer precision for getrusage timers. If the timers are
> incremting by larger values than expected, something is wrong in kernel.
> The precision depends on CONFIG_HZ settings which is represented by the
> BIAS_MAX.
Where does the 1000 come from? If on a slow system, we need to increase
the "factor_nr", right? 
> 
> > And looks like with this patch applied, it works well on powerpc:
> 
> Can you please share the output of the testcase on ppc and ppc64? What
> is the expected timer granularity there?
> 
Looks like the granularity is 10000us:

getrusage04    0  TINFO  :  Expected timers granularity is 10000 us
getrusage04    0  TINFO  :  Using 1 as multiply factor for max [us]time increment (1000+10000us)!
getrusage04    0  TINFO  :  utime:          56us; stime:        1192us
getrusage04    0  TINFO  :  utime:          56us; stime:        2009us
getrusage04    0  TINFO  :  utime:          56us; stime:        4233us
getrusage04    0  TINFO  :  utime:        1227us; stime:        5243us
getrusage04    0  TINFO  :  utime:        1227us; stime:        8541us
getrusage04    0  TINFO  :  utime:        2072us; stime:        8741us
getrusage04    0  TINFO  :  utime:        2602us; stime:       11169us
getrusage04    0  TINFO  :  utime:        2743us; stime:       11747us
getrusage04    0  TINFO  :  utime:        2948us; stime:       12790us
getrusage04    0  TINFO  :  utime:        2948us; stime:       18118us
getrusage04    0  TINFO  :  utime:        2948us; stime:       18596us
getrusage04    0  TINFO  :  utime:        4458us; stime:       20030us
getrusage04    0  TINFO  :  utime:        4458us; stime:       20244us
getrusage04    0  TINFO  :  utime:        4458us; stime:       23432us
getrusage04    0  TINFO  :  utime:        5412us; stime:       24650us
getrusage04    0  TINFO  :  utime:        5412us; stime:       27273us
getrusage04    0  TINFO  :  utime:        6125us; stime:       27909us
getrusage04    0  TINFO  :  utime:        6125us; stime:       27911us
getrusage04    0  TINFO  :  utime:        6125us; stime:       28111us
getrusage04    0  TINFO  :  utime:        6235us; stime:       28513us
getrusage04    0  TINFO  :  utime:        6235us; stime:       28750us
getrusage04    1  TPASS  :  Test Passed


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  reply	other threads:[~2014-12-08 13:09 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-06  1:24 [LTP] questions about getrusage04 Han Pingtian
2014-12-08 12:09 ` Cyril Hrubis
2014-12-08 13:03   ` Han Pingtian [this message]
2014-12-08 13:19     ` Cyril Hrubis
2014-12-08 13:52       ` Han Pingtian

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