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

[Honnappa Nagarahalli]

Hi Yunjian,
               This is not a synchronization problem. The memory is getting allocated and used in the same thread. Are you using a single socket system?

Thanks,
Honnappa

From: wangyunjian <wangyunjian at huawei.com>
Sent: Tuesday, February 8, 2022 2:01 AM
To: Honnappa Nagarahalli <Honnappa.Nagarahalli at arm.com>; dev at dpdk.org; users at dpdk.org
Cc: Feifei Wang <Feifei.Wang2 at arm.com>; Ruifeng Wang <Ruifeng.Wang at arm.com>; Huangshaozhang <huangshaozhang at huawei.com>; dingxiaoxiong <dingxiaoxiong at huawei.com>; nd <nd at arm.com>
Subject: RE: [dpdk-dev][dpdk-users] A problem about memory may not be all-zero allocated by rte_zmalloc_socket()


There is also a condition that the hugepagesz is 1G.

If the hugepagesz is 2M, this problem cannot be repeated.

Thanks,
Yunjian

From: wangyunjian
Sent: Monday, February 7, 2022 10:44 AM
To: 'Honnappa Nagarahalli' <Honnappa.Nagarahalli at arm.com<mailto:Honnappa.Nagarahalli at arm.com>>; dev at dpdk.org<mailto:dev at dpdk.org>; users at dpdk.org<mailto:users at dpdk.org>
Cc: Feifei Wang <Feifei.Wang2 at arm.com<mailto:Feifei.Wang2 at arm.com>>; Ruifeng Wang <Ruifeng.Wang at arm.com<mailto:Ruifeng.Wang at arm.com>>; Huangshaozhang <huangshaozhang at huawei.com<mailto:huangshaozhang at huawei.com>>; dingxiaoxiong <dingxiaoxiong at huawei.com<mailto:dingxiaoxiong at huawei.com>>; nd <nd at arm.com<mailto:nd at arm.com>>
Subject: RE: [dpdk-dev][dpdk-users] A problem about memory may not be all-zero allocated by rte_zmalloc_socket()

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 at arm.com]
Sent: Monday, January 31, 2022 12:22 PM
To: wangyunjian <wangyunjian at huawei.com<mailto:wangyunjian at huawei.com>>; dev at dpdk.org<mailto:dev at dpdk.org>; users at dpdk.org<mailto:users at dpdk.org>
Cc: Feifei Wang <Feifei.Wang2 at arm.com<mailto:Feifei.Wang2 at arm.com>>; Ruifeng Wang <Ruifeng.Wang at arm.com<mailto:Ruifeng.Wang at arm.com>>; Huangshaozhang <huangshaozhang at huawei.com<mailto:huangshaozhang at huawei.com>>; dingxiaoxiong <dingxiaoxiong at huawei.com<mailto:dingxiaoxiong at huawei.com>>; Honnappa Nagarahalli <Honnappa.Nagarahalli at arm.com<mailto:Honnappa.Nagarahalli at arm.com>>; nd <nd at arm.com<mailto:nd at 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 at huawei.com<mailto:wangyunjian at huawei.com>>
Sent: Saturday, January 29, 2022 9:21 PM
To: dev at dpdk.org<mailto:dev at dpdk.org>; users at dpdk.org<mailto:users at dpdk.org>
Cc: Feifei Wang <Feifei.Wang2 at arm.com<mailto:Feifei.Wang2 at arm.com>>; Ruifeng Wang <Ruifeng.Wang at arm.com<mailto:Ruifeng.Wang at arm.com>>; Huangshaozhang <huangshaozhang at huawei.com<mailto:huangshaozhang at huawei.com>>; dingxiaoxiong <dingxiaoxiong at huawei.com<mailto:dingxiaoxiong at 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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