Re: [dpdk-dev] [PATCH v3] mem: command line option to delete hugepage backing files

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Oct 21, 2015 at 04:22:45PM +0000, shesha Sreenivasamurthy (shesha) wrote:
> When an application using huge-pages crash or exists, the hugetlbfs
> backing files are not cleaned up. This is a patch to clean those files.
> There are multi-process DPDK applications that may be benefited by those
> backing files. Therefore, I have made that configurable so that the
> application that does not need those backing files can remove them, thus
> not changing the current default behavior. The application itself can
> clean it up, however the rationale behind DPDK cleaning it up is, DPDK
> created it and therefore, it is better it unlinks it.
> 
> Signed-off-by: Shesha Sreenivasamurthy <shesha@cisco.com>
> ---
>  lib/librte_eal/common/eal_common_options.c | 12 ++++++++++++
>  lib/librte_eal/common/eal_internal_cfg.h   |  1 +
>  lib/librte_eal/common/eal_options.h        |  2 ++
>  lib/librte_eal/linuxapp/eal/eal_memory.c   | 30
> ++++++++++++++++++++++++++++++
>  4 files changed, 45 insertions(+)
> 
<snip>  
> +static int
> +unlink_hugepage_files(struct hugepage_file *hugepg_tbl,
> +		unsigned num_hp_info)
> +{
> +	unsigned socket, size;
> +	int page, nrpages = 0;
> +
> +	/* get total number of hugepages */
> +	for (size = 0; size < num_hp_info; size++)
> +		for (socket = 0; socket < RTE_MAX_NUMA_NODES; socket++)
> +			nrpages += internal_config.hugepage_info[size].num_pages[socket];
> +
> +	for (page = 0; page < nrpages; page++) {
> +		struct hugepage_file *hp = &hugepg_tbl[page];
> +		if (hp->final_va != NULL && unlink(hp->filepath)) {
> +			RTE_LOG(WARNING, EAL, "%s(): Removing %s failed: %s\n",
> +				__func__, hp->filepath, strerror(errno));
> +		}
> +	}
> +	return 0;
> +}
> +
>  /*
>   * unmaps hugepages that are not going to be used. since we originally
> allocate
>   * ALL hugepages (not just those we need), additional unmapping needs to
> be done.
> @@ -1289,6 +1311,14 @@ rte_eal_hugepage_init(void)
>  		goto fail;
>  	}
>  
> +	/* free the hugepage backing files */
> +	if (internal_config.hugepage_unlink &&
> +		unlink_hugepage_files(tmp_hp,
> +			internal_config.num_hugepage_sizes) < 0) {
> +			RTE_LOG(ERR, EAL, "Unlinking hugepage backing files failed!\n");
> +		goto fail;
> +	}
> +
Sorry for the late comment, but...

Rather than adding a whole new function to be called here, can the same effect
not be got by adding in 2/3 lines like:
	if (internal_config.hugepage_unlink)
		unlink(hugetlb[i].filepath)

at line 409 of eal_memory.c where were have done our final mmap of the file.
[You also need the same couple of lines for the 32-bit special case at line 351].
It would be a shorter diff.

/Bruce