Re: [kvm-unit-tests PATCH v3 07/10] arm64: microbench: Add time limit for each individual test

From: Andrew Jones <drjones@redhat.com>
To: Jingyi Wang <wangjingyi11@huawei.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	maz@kernel.org, wanghaibin.wang@huawei.com, yuzenghui@huawei.com,
	eric.auger@redhat.com, prime.zeng@hisilicon.com
Subject: Re: [kvm-unit-tests PATCH v3 07/10] arm64: microbench: Add time limit for each individual test
Date: Sat, 1 Aug 2020 18:13:41 +0200	[thread overview]
Message-ID: <20200801161341.cjaqe7tkw2y7uxjm@kamzik.brq.redhat.com> (raw)
In-Reply-To: <20200731074244.20432-8-wangjingyi11@huawei.com>

On Fri, Jul 31, 2020 at 03:42:41PM +0800, Jingyi Wang wrote:
> Besides using separate running times parameter, we add time limit
> for loop_test to make sure each test should be done in a certain
> time(5 sec here).
> 
> Signed-off-by: Jingyi Wang <wangjingyi11@huawei.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> ---
>  arm/micro-bench.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/arm/micro-bench.c b/arm/micro-bench.c
> index 93bd855..09d9d53 100644
> --- a/arm/micro-bench.c
> +++ b/arm/micro-bench.c
> @@ -22,6 +22,7 @@
>  #include <asm/gic.h>
>  #include <asm/gic-v3-its.h>
>  
> +#define NS_5_SECONDS (5 * 1000 * 1000 * 1000UL)
>  static u32 cntfrq;
>  
>  static volatile bool irq_ready, irq_received;
> @@ -267,23 +268,26 @@ static void loop_test(struct exit_test *test)
>  	uint64_t start, end, total_ticks, ntimes = 0;
>  	struct ns_time total_ns, avg_ns;
>  
> +	total_ticks = 0;
>  	if (test->prep) {
>  		if(!test->prep()) {
>  			printf("%s test skipped\n", test->name);
>  			return;
>  		}
>  	}
> -	isb();
> -	start = read_sysreg(cntpct_el0);
> -	while (ntimes < test->times) {
> +
> +	while (ntimes < test->times && total_ns.ns < NS_5_SECONDS) {

total_ns.ns is now being used uninitialized here. It needs to be
initialized to zero above with total_ns = {}.

I'll do this fixup myself.

Thanks,
drew

> +		isb();
> +		start = read_sysreg(cntpct_el0);
>  		test->exec();
> +		isb();
> +		end = read_sysreg(cntpct_el0);
> +
>  		ntimes++;
> +		total_ticks += (end - start);
> +		ticks_to_ns_time(total_ticks, &total_ns);
>  	}
> -	isb();
> -	end = read_sysreg(cntpct_el0);
>  
> -	total_ticks = end - start;
> -	ticks_to_ns_time(total_ticks, &total_ns);
>  	avg_ns.ns = total_ns.ns / ntimes;
>  	avg_ns.ns_frac = total_ns.ns_frac / ntimes;
>  
> -- 
> 2.19.1
> 
> 