LIBBSD

[Kirspel, Kevin]

Just some quick numbers.  LPC3250 running at 208 MHz, 64MB RAM, 512MB FLASH.

Case #1: Disable the RTEMS callout timer in LIBBSD (kern_timeout.c)
IDLE Task CPUUSE: 99.430%
TIME Task CPUUSE: <0.001%

Case #2: Enable the RTEMS callout timer but do not call "callout_process()" (the timer service routine just resets the timer and quits) .
IDLE Task CPUUSE: 93.144%
TIME Task CPUUSE: 6.282%

So just processing the 1 tick RTEMS timer in LIBBSD's kern_timeout.c takes up 6% of the CPU processing time.

Case #3: Normal callout processing
IDLE Task CPUUSE: 87.116%
TIME Task CPUUSE: 12.672%

Below are the callout functions that are being executed.  The number beside each function is the average number of clocks it took to execute (13MHz base clock).

ipport_tick - 370/28us
pffasttimo -  930/72us
pfslowtimo - 5600/431us
lpe_tick - 4200/323us
_bsd_nd6_timer - 650/50us
usb_power_wdog - 1000/80us
ohci_rhsc_enable - 400/31us

Kevin Kirspel
Electrical Engineer - Sr. Staff
Idexx Roswell
235 Hembree Park Drive
Roswell GA 30076
Tel: (770)-510-4444 ext. 81642
Direct: (770)-688-1642
Fax: (770)-510-4445

-----Original Message-----
From: devel [mailto:devel-bounces at rtems.org] On Behalf Of Sebastian Huber
Sent: Friday, June 30, 2017 1:15 AM
To: devel at rtems.org
Subject: Re: LIBBSD

On 29/06/17 20:02, Kirspel, Kevin wrote:

> For those who run a RTEMS 4.12 single processor application with 
> LIBBSD, what percentage of time does your application spend in the 
> timer server task?  My NXP LPC3250 application spends about 13% of the 
> processor time processing the timer server.  Most of that time is 
> spent processing LIBBSD's kernel callouts.  I am wondering if there is 
> an advantage to only call the FreeBSD's callout_process() function 
> when we know a callout needs to be processed.  This would reduce the 
> number of RTEMS timer fires (which currently fire every tick).

Normally, the timer server should be in the range of 0.x% of CPU time. 
If you have 13%, then you have a lot of timeout processing. What is the reason for this?

--
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber at embedded-brains.de
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Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.

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