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Posted to yarn-issues@hadoop.apache.org by "Zhankun Tang (JIRA)" <ji...@apache.org> on 2019/02/01 14:30:00 UTC
[jira] [Comment Edited] (YARN-9060) [YARN-8851] Phase 1 - Support
device isolation and use the Nvidia GPU plugin as an example
[ https://issues.apache.org/jira/browse/YARN-9060?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16758357#comment-16758357 ]
Zhankun Tang edited comment on YARN-9060 at 2/1/19 2:29 PM:
------------------------------------------------------------
[~sunilg] , Thanks for mentioning this good question.
From what I know, the "snprintf" and "vsnprintf" is, in essence, a buffer copy function and will copy at most "size" (here 512) bytes including the trailing null byte ('\0'). And no "memset" needed before it. We don't need to "memset" a string before "strcopy", right?
And you can check this for details. In below example, it doesn't use "memset" or append "\0".
int n;
int size = 100; /* Guess we need no more than 100 bytes */
char *p, *np;
va_list ap;
if ((p = malloc(size)) == NULL)
return NULL;
while (1) {
/* Try to print in the allocated space */
va_start(ap, fmt);
n = vsnprintf(p, size, fmt, ap);
...
[https://linux.die.net/man/3/snprintf]
was (Author: tangzhankun):
[~sunilg] , Thanks for mentioning this good question.
From what I know, the "snprintf" is, in essence, a buffer copy function and will copy at most "size" (here 512) bytes including the trailing null byte ('\0'). And no "memset" needed before it. We don't need to "memset" a string before "strcopy", right?
And you can check this for details. https://linux.die.net/man/3/snprintf
> [YARN-8851] Phase 1 - Support device isolation and use the Nvidia GPU plugin as an example
> ------------------------------------------------------------------------------------------
>
> Key: YARN-9060
> URL: https://issues.apache.org/jira/browse/YARN-9060
> Project: Hadoop YARN
> Issue Type: Sub-task
> Reporter: Zhankun Tang
> Assignee: Zhankun Tang
> Priority: Major
> Attachments: YARN-9060-trunk.001.patch, YARN-9060-trunk.002.patch, YARN-9060-trunk.003.patch, YARN-9060-trunk.004.patch, YARN-9060-trunk.005.patch, YARN-9060-trunk.006.patch, YARN-9060-trunk.007.patch, YARN-9060-trunk.008.patch, YARN-9060-trunk.009.patch, YARN-9060-trunk.010.patch, YARN-9060-trunk.011.patch, YARN-9060-trunk.012.patch, YARN-9060-trunk.013.patch, YARN-9060-trunk.014.patch, YARN-9060-trunk.015.patch, YARN-9060-trunk.016.patch
>
>
> Due to the cgroups v1 implementation policy in linux kernel, we cannot update the value of the device cgroups controller unless we have the root permission ([here|https://github.com/torvalds/linux/blob/6f0d349d922ba44e4348a17a78ea51b7135965b1/security/device_cgroup.c#L604]). So we need to support this in container-executor for Java layer to invoke.
> This Jira will have three parts:
> # native c-e module
> # Java layer code to isolate devices for container (docker and non-docker)
> # A sample Nvidia GPU plugin
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