Re: [PATCH] CodeSamples/formal/herd: Remove dependency to memory model in cross-klitmus

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Thu, Nov 30, 2017 at 12:24:26AM +0900, Akira Yokosawa wrote:
> On 2017/11/28 16:31:13 -0800, Paul E. McKenney wrote:
> > On Wed, Nov 29, 2017 at 12:24:32AM +0900, Akira Yokosawa wrote:
> >> On 2017/11/26 10:40:24 -0800, Paul E. McKenney wrote:
> >>> On Thu, Nov 23, 2017 at 12:17:57PM +0900, Akira Yokosawa wrote:
> >>>> >From 62491d966a645d08ffc6bb0c5bae9f725458cbec Mon Sep 17 00:00:00 2001
> >>>> From: Akira Yokosawa <akiyks@gmail.com>
> >>>> Date: Thu, 23 Nov 2017 12:07:18 +0900
> >>>> Subject: [PATCH] CodeSamples/formal/herd: Remove dependency to memory model in cross-klitmus
> >>>>
> >>>> Target "cross-klitmus" does not depend on memory model.
> >>>> Remove the implicit dependency of "cd $(LKMM_DIR)" from the recipe.
> >>>>
> >>>> Fixes: ef76630632df ("CodeSamples/formal/herd: Add Makefile and utility script")
> >>>> Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
> >>>
> >>> I applied and pushed both, the first just before the release and the one
> >>> below as the first commit after the release.
> >>>
> >>> I also attached the (very crude) scripts that I use to collect herd
> >>> performance data, just in case they are useful.
> >>
> >> Well, I have no idea how to use absperf-reduce.sh.
> >> It's partly because I'm not good at awk, but I can't figure out what kind of
> >> input and arguments the script assumes.
> > 
> > Good point...
> > 
> >> Can you show me an example?
> >>
> >> I know absperf.sh runs each litmus test 10 times with timeout of 15 minutes.
> >>
> >> I'd be happy to integrate the collection feature into formal/herd/Makefile,
> >> once I know what is expected.
> > 
> > So you run absperf.sh and feed its output into absperf-reduce.sh as
> > its standard input.
> > 
> > I normally dump the absperf.sh to a file and then run absperf-reduce.sh
> > on that file.  The output is the litmus-test name followed by the
> > average, minimum, and maximum runtimes for that litmus test.
> > 
> > One oddity is that both scripts expect the scripts to be in the
> > directory litmus-tests/absperf -- this is hard-coded into absperf.sh's
> > for-loop and into the first pattern of absperf-reduce.sh's awk script
> > (the "/^litmus-tests/ {" line).
> 
> Ah, this is the key point I could not figure out.
> Now I can run the scripts using short litmus tests.
> 
> We also need memory model files in the current directory.
> 
> So the current scheme in CodeSamples/formal/herd/ of "cd memory-model; herd7 ..."
> conflicts with the above assumption.

Indeed, and one more reason to rewrite.  ;-)

> Let me think what approach is suitable for perfbook's CodeSamples.
> This may take a while.

Not an emergency as far as I know, especially given that I can continue
using the old scripts.  ;-)

							Thanx, Paul

>        Thanks, Akira
> 
> > 
> > So here is how the absperf-reduce.sh script operates, in the likely
> > event that you would prefer to just rewrite it (which would be fine
> > by me):
> > 
> > o	Each awk statement block is preceded by a pattern, and
> > 	contains a "{}"-enclosed sequence of statements.  These
> > 	statements are executed only when the pattern matches the
> > 	current line.  The special pattern "END" executes after
> > 	the input has been consumed and processed.
> > 
> > o	The "/^litmus-tests/" matches lines beginning with "litmus-tests".
> > 	These lines are those "echo"ed by absperf.sh.  This check
> > 	relies on the fact that herd7 doesn't output lines beginning
> > 	with "litmus-tests", which is admittedly a very fragile
> > 	approach.
> > 
> > 	Upon match, the variable "curtest" is set to the first word
> > 	on the current line (which is the litmus-test pathname)
> > 	and the variable "testrun" is set to zero to say that we
> > 	do not yet have any evidence that the test ran to completion.
> > 
> > o	The "/^Test/" is output by herd7, and indicates that the
> > 	litmus test actually completed.  So we set "testran" to 1.
> > 
> > o	The "/maxresident)k/" matches output from /bin/time.  If
> > 	herd7 ran, the following lines parse the /bin/time output,
> > 	and accumulate the number of runs, the total time, and
> > 	the minimum and maximum time in awk associative arrays.
> > 
> > 	(In awk, 'a["efwefew"]++' is a perfectly valid expression,
> > 	and it increments the element of "a" indexed by the string
> > 	"efwefew".  I am pretty sure that most scripting languages
> > 	do this these days, but it was pretty surprising back when
> > 	awk came out with it.)
> > 
> > o	The "END" loops through all elements of the array, with
> > 	the variable "i" taking on each index of that array in
> > 	turn.  The print statement thus prints the litmus test
> > 	name along with its statistics.
> > 
> > I then hand-edited the output to make various tables in email and Table
> > 12.3 in perfbook.
> > 
> > Why awk?  Back when I was starting scripting languages, it was the only
> > one availalble on UNIX.  This would have been some time in the 1980s.
> > It is very unlikely to be the best choice for someone starting out
> > today.  ;-)
> > 
> > 							Thanx, Paul
> > 
> > 
>