On Mon, 13 Aug 2012, Jain Priyanka-B32167 wrote:

Hello Clark,

Did you have the chance to test the patch.

Thanks
Priyanka

-----Original Message-----
From: linux-rt-users-owner@vger.kernel.org [mailto:linux-rt-users-owner@vger.kernel.org] On Behalf Of Jain Priyanka-B32167
Sent: Tuesday, August 07, 2012 9:32 AM
To: Clark Williams
Cc: linux-rt-users@vger.kernel.org; dvhart@linux.intel.com; rostedt@goodmis.org; tglx@linutronix.de; Srivastava Rajan-B34330; Aggrwal Poonam-B10812
Subject: RE: [PATCH 1/2][RFC] Add README_cyclicload

Thanks Clark

Waiting for the results at your end.


Regards
Priyanka

-----Original Message-----
From: Clark Williams [mailto:williams@redhat.com] 
Sent: Monday, August 06, 2012 7:29 PM
To: Jain Priyanka-B32167
Cc: linux-rt-users@vger.kernel.org; dvhart@linux.intel.com; rostedt@goodmis.org; tglx@linutronix.de; Srivastava Rajan-B34330; Aggrwal Poonam-B10812
Subject: Re: [PATCH 1/2][RFC] Add README_cyclicload

Priyanka,

For some reason all of us that work on rt-tests were busy last week.
I'll apply these patches and try out cyclicload this week.

Clark

On Mon, 6 Aug 2012 04:00:15 +0000
Jain Priyanka-B32167 [off-list ref] wrote:

quoted

Hi,

Waiting for the comments on this tool.

Thanks
Priyanka

-----Original Message-----
From: Jain Priyanka-B32167
Sent: Wednesday, August 01, 2012 10:37 AM
To: linux-rt-users@vger.kernel.org; williams@redhat.com; 
dvhart@linux.intel.com
Cc: rostedt@goodmis.org; tglx@linutronix.de; Srivastava Rajan-B34330; 
Aggrwal Poonam-B10812; Jain Priyanka-B32167
Subject: [PATCH 1/2][RFC] Add README_cyclicload

Cyclicload program is designed to simulate load at regular intervals in form of one or two threads.

Signed-off-by: Priyanka Jain <redacted>
---
 src/cyclictest/README_cyclicload |  147 
++++++++++++++++++++++++++++++++++++++
 1 files changed, 147 insertions(+), 0 deletions(-)  create mode 
100644 src/cyclictest/README_cyclicload

diff --git a/src/cyclictest/README_cyclicload 

b/src/cyclictest/README_cyclicload
new file mode 100644
index 0000000..f1e99bf

--- /dev/null
+++ b/src/cyclictest/README_cyclicload

@@ -0,0 +1,147 @@
+DESCRIPTION
+-------------
+
+The cyclicload program is developed above existing cyclictest application.
+It is basically designed to simulate specified load at regular 
+intervals in addition to cyclictest functionality.
+It can simulate one or two load threads.
+
+
+Why it is required?
+---------------------
+It is required to test system performance under a specified load 
+along with tracking latency of simulated load thread.
+
+
+Example use case
+--------------------
+For products like LTE, L2 layer runs in form of two threads.
+-MAC layer thread runs at highest RT priority producing a fixed load 
+at regular intervals and -second thread run at lower RT priority or 
+in non-rt priority  producing some load in each interval depending 
+upon availability of CPU.
+Requirement is to test system under this load as well as to track 
+latency of highest priority RT thread which is MAC thread in example 
+usecase.
+
+
+What does it do?
+------------------
+It creates one or two load generating thread/s.
+1)load1 thread (timer thread)
+2)load2 thread
+priority, nice value, load % as input via command line
+
+-cyclictest funcationality like latency measurement
+
+
+How does it work
+-----------------
+It uses generate_load loop function to simualte load.
+First it caliberate required loop_count per unit time per CPU.
+It stores this data in some file.
+For subsequent runs, it uses this caliberated data to generate load 
+if form of one or two threads .
+It keeps on tracking the latency of RT thread.
+More in Design Overview section.
+
+
+Recommended Settings
+----------------------
+-First run is recommended to be run with no or least load for accuracy.
+-should be run with sudo or root permission.
+-caliberation routine produces calinerate_ount file in runnign directory.
+	If one don't have permission in that dir, path should be changed in
+	FILENAME or one can exploit shared memory method.
+-Atleast one thread should be of RT priority. This thread takes priority of
+	cyclictest as its priority.
+-cyclictest applcication should be run with SCHED_OTHER policy.
+-recommended to run in quiet mode (-q) in background.
+TODO: add option to take filepath from cmd line
+
+
+Cmd line usage/examples
+------------------------
+New command line arguments:
+ "-x       --load_t1         load in percentage for t1 thread\n"
+ "-X       --load_t2         load in percentage for t2 thread\n"
+ "-z       --priority_t2     priority of t2 thread\n"
+ "-Z       --nice_t2         nice value of t2 thread\n"
+
+If both load_t1 and load_t2 are zero, it behaves as default 
+cyclictest application
+
+For uniprocessor:
+	#sudo ./cyclictest -p 99 -c 1 -d 0 -x 40 -X 30 -q -D 600&
+
+For multiprocessor:
+	#sudo ./cyclcitest -p 99 -c 1 -d 0 -x 40 -X 30 -q -D 600 -S&
+
+
+
+Future Enhancements
+-------------------
+Maintain statistics of average load produces.
+invalidate cache in each interval to make it close to actual scenario.
+can be scalable to produce n number of load threads.
+
+
+Design Overview
+--------------
+---------------
+
+The logic to simulate load has been added above existing cyclictest application.
+
+Threads
+--------
+cyclicload : main process
+--------------------------
+-parse input arguments.
+
+-for first run : create caliberate thread.
+	store caliberated count in caliberate_count file -for subsequent runs:
+	read caliberated count from file and use that count to simulate defined load.
+
+-create t load1threads (t depending on cmdlime args, for smp system = 
+num of cores, one thread per core)
+
+-update stats periodically while !shutdown -print stats periodically 
+depending on cmdline args while !shutdown
+
+
+caliberate thread
+------------------
+-is created only once for the first run of cyclicload -run at highest 
+RT priority.
+-affine itself turn by turn to each cpu. (for all cpus for multicore
+system) -caliberate count per unit (ms by default) per cpu -store per 
+cpu data in caliberate_count_array -recommended to be run with no or 
+least load.
+
+
+load1 thread(timer thread)
+---------------------------
+-run at priority parsed in main routine -recommended to run at 
+highest RT priority -creates load2_thread (optional only if on load2 
+is
+nonzero) -calculate number of loops to execute to generate defined 
+load by
+	using caliberate_count_array and load percentage parsed in main 
+routine -reduced interval = interval(window) - duration for load_t1 
+-while loop until !shutdown
+	-generate load_t1 load
+	-sleep for reduced interval
+	-calculate latency (cosumes around 1%-2% cpu)
+	-discard off remaining load if window expires
+	-set next_window_started flag to 1
+	-signal load2_thread about next window
+-overhead: consumes 1-2% cpu for latency maintainenance, etc 
+-variation in produced load : 0%-2% of full cpu utilization
+
+
+load2_thread
+------------
+generate load_t2 load
+wait for next window to start
+if window expires before generate load_t2 finishes,
+	discard off remaining load
+	restart generate load_t2 load
+variation in produced load : 0%-1% of full cpu utilization
--

1.7.4.1

Okay, the patches apply cleanly, and it builds cleanly.
I admit I didn't look closely at what you're trying to do, but I'm a 
little skeptical that this is a real load instead of just a task spinning 
at an rt prio, but I could be wrong.

However, the major rule when doing stuff in rt-tests is don't break 
cyclictest!

When I tried to run cyclictest with your patches applied, I immediately 
observed a lot of broken behaviour, even when I tried your -x0 and -X0 
(although that shouldn't be necessary).

Basically everything moved at a crawl. So, I'm not going to look any 
closer at this until cyclictest works exactly as before. Sorry.

I know you are trying to simulate a specific load and not a generic one, 
however you might want to take a look at rteval.

rteval basically runs some standard benchmarks such as hackbench and then 
runs cyclictest at the same time to see if we can break the behaviour of 
cyclictest. Have a look at that too please and see if it might meet your 
needs.

You can fetch it here.
git://git.kernel.org/pub/scm/linux/kernel/git/clrkwllms/rteval.git>

Thanks
John