On Tue, 26 Jan 2021, Daniel Wagner wrote:

On Tue, Jan 26, 2021 at 12:55:33AM -0500, John Kacur wrote:

quoted

Well, --smp historically combined -a -t and threads at the same priority
You could argue that it is reasonable for -a to automatically imply -t
but I have had debates with people about this and we settled on -a just 
specifies the affinity, and the default number of threads is one unless
you use -t.

My thinking is if you set an affinity mask, you want also to assign a
thread to the CPUs. If not what's the point to set an affinity mask
without a thread on it. Though the user is able to overwrite this
by providing the -t options along side the -a option.

Not necessarily, but you want to limit where the threads, no matter
how few or how many run. As I said, it's not an unreasonable default,
but it is not the current default of 1 unless you specify -t
I suggest we stick with the current default in this clean-up effort.
We can discuss if there are some better defaults after this effort is 
complete.

quoted

I'm not sure what you mean by this makes cyclictest behave the way the 
rest of rt-tests does, the rest of rt-tests should match what cyclitest 
does.

As I wrote, make cyclictest behave the same way as the to other tools
when -a/-t is used.

quoted

That said, I did some quick runs of signaltest and -a seems broken,
sigh.

Is it broken without my patches or with my patches? What is broken?

I haven't done a git bisect or something of that sort to determine if your 
patches broke it, but here's what I see. (running on non-rt laptop now, so 
ignore numbers), but it looks like at least the -t option requiring an 
argument existed before your changes, but your changes to affinity 
probably could use some more testing.

The following is okay

./signaltest  -a1-4
2.00 1.52 1.14 2/1079 6541          

T: 0 ( 6537) P: 0 C:  14896 Min:      3 Act:    4 Avg:   26 Max:     366


The following is broken, the default without an argument should be 2
./signaltest  -t
./signaltest: option requires an argument -- 't'

In the following note that threads other than thread 0 didn't appear
on the screen until after the ctrl-c

./signaltest -t9 -a1-4
1.11 1.14 1.14 2/1075 6864          

T: 0 ( 6856) P: 0 C:   1649 Min:     38 Act:  511 Avg:  457 Max:    4911
^CT: 0 ( 6856) P: 0 C:   1660 Min:     38 Act:  554 Avg:  457 Max:    4911
T: 1 ( 6857) P: 0 C:   1660 Min:     38 Act:  490 Avg: 1090 Max:   15024
T: 2 ( 6858) P: 0 C:   1660 Min:     38 Act:  449 Avg: 1091 Max:   15053
T: 3 ( 6859) P: 0 C:   1660 Min:     38 Act:  412 Avg: 1091 Max:   15075
T: 4 ( 6860) P: 0 C:   1660 Min:     38 Act:  378 Avg: 1090 Max:   15081
T: 5 ( 6861) P: 0 C:   1659 Min:     38 Act:  517 Avg: 1091 Max:   15072
T: 6 ( 6862) P: 0 C:   1659 Min:     38 Act:  485 Avg: 1091 Max:   15067
T: 7 ( 6863) P: 0 C:   1659 Min:     38 Act:  522 Avg: 1091 Max:   12832
T: 8 ( 6864) P: 0 C:   1659 Min:     38 Act:  549 Avg: 1091 Max:   12839


etc, it's broken in many ways.