Re: [dpdk-dev] About the shared flock for hugepage files

[Jim Thompson <jim@netgate.com>]

Bakari,

This is so you can have > 1 DPDK application on a machine and they won't use each other's hugepages. 

See, for example the comments in clear_hugedir()

http://dpdk.org/browse/dpdk/tree/lib/librte_eal/linuxapp/eal/eal_hugepage_info.c#n198

Jim

> On Sep 11, 2017, at 9:16 PM, 白长敏 <912873551@qq.com> wrote:
> 
> Hi, everyone,
> 
> 
>    I'm a developer from china, now i have a problem is about the shared flock for hugepage files in the function of "map_all_hugepages()".
> 
> 
> as follows:
> ---------------------------------------------------------------------------------------------------
> /* set shared flock on the file. */
> 
> 
> if (flock(fd, LOCK_SH | LOCK_NB) == -1) {
> 
> 
>        RTE_LOG(DEBUG, EAL, "%s(): Locking file failed:%s \n", __func__, strerror(errno));
> 
> 
>        close(fd);
> 
> 
>        return i;
> 
> 
> }
> 
> 
> close(fd);
> 
> --------------------------------------------------------------------------------------------------
> there, it gives a shared flock to each hugepage file in /mnt/huge, and close it right away. 
> 
> 
> it makes me puzzled. Why? What doing that is for? 
> 
> 
> I'm looking forward to your reply, thank you very much.
> 
> 
> best regards,
> Bakari.