Re: [LTP] [PATCH v1] starvation.c: New case for sched starvation

[Wei Gao via ltp <ltp@lists.linux.it>]

On Tue, May 09, 2023 at 07:52:56AM +0200, Petr Vorel wrote:
> > On Fri, May 05, 2023 at 07:31:37PM +0200, Petr Vorel wrote:
> > > Hi Wei,
> 
> > > > +static struct tst_test test = {
> > > > +	.test_all = do_test,
> > > > +	.setup = setup,
> > > > +	.forks_child = 1,
> > > > +	.needs_checkpoints = 1,
> > > > +	.max_runtime = 120,
> > > Are you sure 2 min is enough? Maybe we need to use tst_remaining_runtime() to
> > > check if we're not running out of time.
> 
> > Seems difficult to check with tst_remaining_runtime since i can use code such as:
> > while(tst_remaining_runtime()) 
> > 	wait_for_pid();
> 
> If you don't know how to use tst_remaining_runtime() how about getting
> inspiration from lib/newlib_tests/test_runtime01.c ?
What i mean is i can not use while or do loop to check tst_remaining_runtime, since 
the last function wait_for_pid() already hold(block) the current process and you do not need 
and can not use tst_remaining_runtime(). Sorry if any misunderstood.

> 
> static void run(void)
> {
> 	int runtime;
> 
> 	tst_res(TINFO, "...");
> 
> 	do {
> 		runtime = tst_remaining_runtime();
> 		tst_res(TINFO, "Remaining runtime %d", runtime);
> 		sleep(1);
> 	} while (runtime);
> 
> 	tst_res(TPASS, "Test passed");
> }
> 
> static struct tst_test test = {
> 	.test_all = run,
> 	.max_runtime = 120,
> };
> 
> => Also, it's a question, how long should the test be running.
> Is it worth to be running for 2 mins? It's kind of stress test, right?
> But even that wouldn't be 30 sec enough?
Normally the default value which i set will spend ~30s i test in virtual machine.
I suppose 2mins max_runtime should be safe enough. 
Yes it can be taken as stress test, you need a big loop number to let test run.

In latest v2 patch the number of loop and max_runtime both configurable, so if your machine 
is too slow maybe you need adjust parameter.
> 
> Kind regards,
> Petr
> 
> > > Also, if we set getopt to choose number of options, we'd need to adjust it by
> > > tst_set_max_runtime().
> 
> > > Kind regards,
> > > Petr
> 
> > > > +};

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