linux-kernel - Re: [PATCH rcu-dev 1/2] rcuperf: Add ability to increase object allocation size

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Message-ID: <20200306013714.GR2935@paulmck-ThinkPad-P72>
Date:   Thu, 5 Mar 2020 17:37:14 -0800
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org, Davidlohr Bueso <dave@...olabs.net>,
        Josh Triplett <josh@...htriplett.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        rcu@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        urezki@...il.com
Subject: Re: [PATCH rcu-dev 1/2] rcuperf: Add ability to increase object
 allocation size

On Thu, Mar 05, 2020 at 08:16:25PM -0500, Joel Fernandes (Google) wrote:
> This allows us to increase memory pressure dynamically using a new
> rcuperf boot command line parameter called 'rcumult'.
> 
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>

Looks plausible to me at a very quick first glance.  Uladzislau, thoughts?

							Thanx, Paul

> ---
>  kernel/rcu/rcuperf.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
> index a4a8d097d84d9..16dd1e6b7c09f 100644
> --- a/kernel/rcu/rcuperf.c
> +++ b/kernel/rcu/rcuperf.c
> @@ -88,6 +88,7 @@ torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
>  torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
>  torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
>  torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() perf test?");
> +torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
>  
>  static char *perf_type = "rcu";
>  module_param(perf_type, charp, 0444);
> @@ -635,7 +636,7 @@ kfree_perf_thread(void *arg)
>  		}
>  
>  		for (i = 0; i < kfree_alloc_num; i++) {
> -			alloc_ptr = kmalloc(sizeof(struct kfree_obj), GFP_KERNEL);
> +			alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
>  			if (!alloc_ptr)
>  				return -ENOMEM;
>  
> @@ -722,6 +723,8 @@ kfree_perf_init(void)
>  		schedule_timeout_uninterruptible(1);
>  	}
>  
> +	pr_alert("kfree object size=%lu\n", kfree_mult * sizeof(struct kfree_obj));
> +
>  	kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
>  			       GFP_KERNEL);
>  	if (kfree_reader_tasks == NULL) {
> -- 
> 2.25.0.265.gbab2e86ba0-goog
>