linux-kernel - Re: [PATCH net-next v7 01/15] mm: page_frag: add a test module for page

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Message-ID: <a0396334-e9fa-9ceb-5d6e-7bf798ed545a@huawei.com>
Date: Wed, 19 Jun 2024 20:57:51 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: wang wei <a929244872@....com>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Alexander Duyck
	<alexander.duyck@...il.com>, Andrew Morton <akpm@...ux-foundation.org>,
	<linux-mm@...ck.org>
Subject: Re: [PATCH net-next v7 01/15] mm: page_frag: add a test module for
 page_frag

On 2024/6/18 22:45, wang wei wrote:
> 
>>+
>>+static struct objpool_head ptr_pool;
>>+static int nr_objs = 512;
>>+static atomic_t nthreads;
>>+static struct completion wait;
>>+static struct page_frag_cache test_frag;
>>+
>>+static int nr_test = 5120000;
>>+module_param(nr_test, int, 0600);
> 
> 
> "S_IRUSR | S_IWUSR" is better than "0600".

Yes, it is better.
But as we do the testing in module init, it seems we could just
use module_param(nr_test, int, 0) instead.

> 
> 
>>+MODULE_PARM_DESC(nr_test, "number of iterations to test");
>>+
>>+static bool test_align;
>>+module_param(test_align, bool, 0600);
>>+MODULE_PARM_DESC(test_align, "use align API for testing");
>>+
>>+static int test_alloc_len = 2048;
>>+module_param(test_alloc_len, int, 0600);
>>+MODULE_PARM_DESC(test_alloc_len, "alloc len for testing");
>>+
>>+static int test_push_cpu;
>>+module_param(test_push_cpu, int, 0600);
>>+MODULE_PARM_DESC(test_push_cpu, "test cpu for pushing fragment");
>>+
>>+static int test_pop_cpu;
>>+module_param(test_pop_cpu, int, 0600);
>>+MODULE_PARM_DESC(test_pop_cpu, "test cpu for popping fragment");
>>+
>>+static int page_frag_pop_thread(void *arg)
>>+{
>>+	struct objpool_head *pool = arg;
>>+	int nr = nr_test;
>>+
>>+	pr_info("page_frag pop test thread begins on cpu %d\n",
>>+		smp_processor_id());
>>+
>>+	while (nr > 0) {
>>+		void *obj = objpool_pop(pool);
>>+
>>+		if (obj) {
>>+			nr--;
>>+			page_frag_free(obj);
>>+		} else {
>>+			cond_resched();
>>+		}
>>+	}
>>+
>>+	if (atomic_dec_and_test(&nthreads))
>>+		complete(&wait);
>>+
>>+	pr_info("page_frag pop test thread exits on cpu %d\n",
>>+		smp_processor_id());
>>+
>>+	return 0;
>>+}
>>+
>>+static int page_frag_push_thread(void *arg)
>>+{
>>+	struct objpool_head *pool = arg;
>>+	int nr = nr_test;
>>+
>>+	pr_info("page_frag push test thread begins on cpu %d\n",
>>+		smp_processor_id());
>>+
>>+	while (nr > 0) {
>>+		void *va;
>>+		int ret;
>>+
>>+		if (test_align)
>>+			va = page_frag_alloc_align(&test_frag, test_alloc_len,
>>+ GFP_KERNEL, SMP_CACHE_BYTES);
> 
> 
> Every page fragment max size is PAGE_FRAG_CACHE_MAX_SIZE, hence the value of test_alloc_len needs to be checked.
> 

yes, that needs to be checked.
limit the test_alloc_len to PGAE_SIZE seems better, as we may fail back to
order 0 page.

>