linux-kernel - Re: [PATCH] misc: kgdbts: Display progress of asynchronous tests

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Date:   Thu, 14 Dec 2017 09:20:56 -0600
From:   Jason Wessel <jason.wessel@...driver.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>
CC:     <kgdb-bugreport@...ts.sourceforge.net>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-kernel@...r.kernel.org>, <patches@...aro.org>
Subject: Re: [PATCH] misc: kgdbts: Display progress of asynchronous tests

On 12/12/2017 06:10 AM, Daniel Thompson wrote:
> kgdbts includes a couple of different "thrashing" style tests that
> may have long runtimes (especially on simulated platforms) and which
> run asynchronously. This is uncomfortable for interactive use and
> makes setting timeouts tricky for automatic use.


Do you know which test was specifically causing a problem?  It might not be documented anywhere but I had usually started a user space process which quickly created and deleted user space processes in order to make the kgdbts tests complete quickly.

I don't really see any issue with emitting a printk to indicate progress as it is debug only and test specific.  As you know printk's change timing.  If I had a dime for each time I had seen a problem go away when I started adding printk's I'd have at least a 50 cents.  :-)


Jason.

PS.  Added this to kgdb-next and I'll put in a request to get kgdb-next added back to the linux-next builder.

> 
> Fix by providing a optional means to show progress during these tests.
> Selecting 100 is somewhat arbitrary but it matches the step used on
> the synchronous tests, is large enough to keep the call to printk
> from invalidating the testing and is human enough to "feel about
> right".
> 
> Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>
> ---
>   drivers/misc/kgdbts.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
> index 24108bfad889..6193270e7b3d 100644
> --- a/drivers/misc/kgdbts.c
> +++ b/drivers/misc/kgdbts.c
> @@ -400,10 +400,14 @@ static void skip_back_repeat_test(char *arg)
>   	int go_back = simple_strtol(arg, NULL, 10);
> 
>   	repeat_test--;
> -	if (repeat_test <= 0)
> +	if (repeat_test <= 0) {
>   		ts.idx++;
> -	else
> +	} else {
> +		if (repeat_test % 100 == 0)
> +			v1printk("kgdbts:RUN ... %d remaining\n", repeat_test);
> +
>   		ts.idx -= go_back;
> +	}
>   	fill_get_buf(ts.tst[ts.idx].get);
>   }
> 
> --
> 2.14.3
>