RE: [dpdk-dev][dpdk-users] A problem about memory may not be all-zero allocated by rte_zmalloc_socket()

[wangyunjian <wangyunjian@huawei.com>]

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Hi, Honnappa



This problem is probability. Test case need to be executed multiple times.



The test steps and code are as follows:



/home/dpdk #./arm64-armv8a-linuxapp-gcc/app/dpdk-testpmd --legacy-mem  -c 0xC  -m 8192



app/test-pmd/testpmd.c | 14 ++++++++++++++

1 file changed, 14 insertions(+)



diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c

index 55eb293cc0..3c127f9623 100644

--- a/app/test-pmd/testpmd.c

+++ b/app/test-pmd/testpmd.c

@@ -4251,6 +4251,20 @@ main(int argc, char** argv)

                  rte_stats_bitrate_reg(bitrate_data);

        }

#endif

+

+       printf("start test rte_zmalloc_socket\n");

+       char *a;

+       while((a = rte_zmalloc_socket(NULL, 1024 * 1024, 0, SOCKET_ID_ANY)) != NULL) {

+                for (int i = 0; i < 1024 * 1024; i++) {

+                          if (a[i] != 0) {

+                                   printf("a[%d] = %d\n",i,a[i]);

+                          }

+                          a[i] = 255; // This assignment is important. It can increase the probability.

+                }

+       }

+       printf("end test rte_zmalloc_socket\n");

+       return EXIT_SUCCESS;

+

#ifdef RTE_LIB_CMDLINE

        if (strlen(cmdline_filename) != 0)

                  cmdline_read_from_file(cmdline_filename);

Thanks,
Yunjian

From: Honnappa Nagarahalli [mailto:Honnappa.Nagarahalli@arm.com]
Sent: Monday, January 31, 2022 12:22 PM
To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org; users@dpdk.org
Cc: Feifei Wang <Feifei.Wang2@arm.com>; Ruifeng Wang <Ruifeng.Wang@arm.com>; Huangshaozhang <huangshaozhang@huawei.com>; dingxiaoxiong <dingxiaoxiong@huawei.com>; Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>; nd <nd@arm.com>
Subject: RE: [dpdk-dev][dpdk-users] A problem about memory may not be all-zero allocated by rte_zmalloc_socket()

Hi Yunjian,
                That's interesting. Is it possible to elaborate the use case or possibly provide the code snippet?

It is possible that it is a synchronization problem due to relaxed memory model that Arm architecture uses. There could be a barrier missing in the code.

Thanks,
Honnappa

From: wangyunjian <wangyunjian@huawei.com<mailto:wangyunjian@huawei.com>>
Sent: Saturday, January 29, 2022 9:21 PM
To: dev@dpdk.org<mailto:dev@dpdk.org>; users@dpdk.org<mailto:users@dpdk.org>
Cc: Feifei Wang <Feifei.Wang2@arm.com<mailto:Feifei.Wang2@arm.com>>; Ruifeng Wang <Ruifeng.Wang@arm.com<mailto:Ruifeng.Wang@arm.com>>; Huangshaozhang <huangshaozhang@huawei.com<mailto:huangshaozhang@huawei.com>>; dingxiaoxiong <dingxiaoxiong@huawei.com<mailto:dingxiaoxiong@huawei.com>>
Subject: [dpdk-dev][dpdk-users] A problem about memory may not be all-zero allocated by rte_zmalloc_socket()

Hi, all

There's a problem that the memory are allocated by rte_zmalloc_socket()
may not be all-zero on the ARM platform.

However, the x86 platform does not have this problem.


Any ideas ?


Thanks,

Yunjian


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