Re: [dpdk-dev] [PATCH v4] eal: make hugetlb initialization more robust

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-05-12 00:44, Jianfeng Tan:
> This patch adds an option, --huge-trybest, to use a recover mechanism to
> the case that there are not so many hugepages (declared in sysfs), which
> can be used. It relys on a mem access to fault-in hugepages, and if fails

relys -> relies

> with SIGBUS, recover to previously saved stack environment with
> siglongjmp().
> 
> Besides, this solution fixes an issue when hugetlbfs is specified with an
> option of size. Currently DPDK does not respect the quota of a hugetblfs
> mount. It fails to init the EAL because it tries to map the number of free
> hugepages in the system rather than using the number specified in the quota
> for that mount.

It looks to be a bug. Why adding an option?
What is the benefit of the old behaviour, not using --try-best?

> +static sigjmp_buf jmpenv;
> +
> +static void sigbus_handler(int signo __rte_unused)
> +{
> +	siglongjmp(jmpenv, 1);
> +}
> +
> +/* Put setjmp into a wrap method to avoid compiling error. Any non-volatile,
> + * non-static local variable in the stack frame calling sigsetjmp might be
> + * clobbered by a call to longjmp.
> + */
> +static int wrap_sigsetjmp(void)
> +{
> +	return sigsetjmp(jmpenv, 1);
> +}

Please add the word "huge" to these variables and functions.

> +static struct sigaction action_old;
> +static int need_recover;
> +
> +static void
> +register_sigbus(void)
> +{
> +	sigset_t mask;
> +	struct sigaction action;
> +
> +	sigemptyset(&mask);
> +	sigaddset(&mask, SIGBUS);
> +	action.sa_flags = 0;
> +	action.sa_mask = mask;
> +	action.sa_handler = sigbus_handler;
> +
> +	need_recover = !sigaction(SIGBUS, &action, &action_old);
> +}
> +
> +static void
> +recover_sigbus(void)
> +{
> +	if (need_recover) {
> +		sigaction(SIGBUS, &action_old, NULL);
> +		need_recover = 0;
> +	}
> +}

Idem, Please add the word "huge".