Re: [PATCH v2] mem: command line option to delete hugepage backing files

[Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>]

Hi Shesha,

A few things:
- For some reason the patch didn't upload properly to patchwork and the 
last bit of the patch is missing.
   The following link shows that the patch fails basic testing/compilation:
   http://dpdk.org/ml/archives/test-report/2015-October/000352.html
- You seem to be sending two copies of the same patch.
- Please update patchwork status for v1 patch. I think this is because 
there were two copies of it [patch id 7606]

On 20/10/2015 18:29, 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   | 39
> ++++++++++++++++++++++++++++++
>   4 files changed, 54 insertions(+)
>
> diff --git a/lib/librte_eal/common/eal_common_options.c
> b/lib/librte_eal/common/eal_common_options.c
> index 1f459ac..5fe6374 100644
> --- a/lib/librte_eal/common/eal_common_options.c
> +++ b/lib/librte_eal/common/eal_common_options.c
> @@ -79,6 +79,7 @@ eal_long_options[] = {
>   	{OPT_MASTER_LCORE,      1, NULL, OPT_MASTER_LCORE_NUM     },
>   	{OPT_NO_HPET,           0, NULL, OPT_NO_HPET_NUM          },
>   	{OPT_NO_HUGE,           0, NULL, OPT_NO_HUGE_NUM          },
> +	{OPT_HUGE_UNLINK,       0, NULL, OPT_HUGE_UNLINK_NUM      },
>   	{OPT_NO_PCI,            0, NULL, OPT_NO_PCI_NUM           },
>   	{OPT_NO_SHCONF,         0, NULL, OPT_NO_SHCONF_NUM        },
>   	{OPT_PCI_BLACKLIST,     1, NULL, OPT_PCI_BLACKLIST_NUM    },
> @@ -722,6 +723,10 @@ eal_parse_common_option(int opt, const char *optarg,
>   		conf->no_hugetlbfs = 1;
>   		break;
>   
> +	case OPT_HUGE_UNLINK_NUM:
> +		conf->hugepage_unlink = 1;
> +		break;
> +
>   	case OPT_NO_PCI_NUM:
>   		conf->no_pci = 1;
>   		break;
> @@ -856,6 +861,12 @@ eal_check_common_options(struct internal_config
> *internal_cfg)
>   		return -1;
>   	}
>   
> +	if (internal_cfg->no_hugetlbfs && internal_cfg->hugepage_unlink) {
> +		RTE_LOG(ERR, EAL, "Option --"OPT_HUGE_UNLINK" cannot "
> +			"be specified together with --"OPT_NO_HUGE"\n");
> +		return -1;
> +	}
> +
>   	if (rte_eal_devargs_type_count(RTE_DEVTYPE_WHITELISTED_PCI) != 0 &&
>   		rte_eal_devargs_type_count(RTE_DEVTYPE_BLACKLISTED_PCI) != 0) {
>   		RTE_LOG(ERR, EAL, "Options blacklist (-b) and whitelist (-w) "
> @@ -906,6 +917,7 @@ eal_common_usage(void)
>   	       "  -h, --help          This help\n"
>   	       "\nEAL options for DEBUG use only:\n"
>   	       "  --"OPT_NO_HUGE"           Use malloc instead of hugetlbfs\n"
> +	       "  --"OPT_HUGE_UNLINK"       Unlink hugepage backing file after
> initalization\n"
>   	       "  --"OPT_NO_PCI"            Disable PCI\n"
>   	       "  --"OPT_NO_HPET"           Disable HPET\n"
>   	       "  --"OPT_NO_SHCONF"         No shared config (mmap'd files)\n"
> diff --git a/lib/librte_eal/common/eal_internal_cfg.h
> b/lib/librte_eal/common/eal_internal_cfg.h
> index e2ecb0d..84b075f 100644
> --- a/lib/librte_eal/common/eal_internal_cfg.h
> +++ b/lib/librte_eal/common/eal_internal_cfg.h
> @@ -64,6 +64,7 @@ struct internal_config {
>   	volatile unsigned force_nchannel; /**< force number of channels */
>   	volatile unsigned force_nrank;    /**< force number of ranks */
>   	volatile unsigned no_hugetlbfs;   /**< true to disable hugetlbfs */
> +	volatile unsigned hugepage_unlink; /** < true to unlink backing files */
>   	volatile unsigned xen_dom0_support; /**< support app running on Xen
> Dom0*/
>   	volatile unsigned no_pci;         /**< true to disable PCI */
>   	volatile unsigned no_hpet;        /**< true to disable HPET */
> diff --git a/lib/librte_eal/common/eal_options.h
> b/lib/librte_eal/common/eal_options.h
> index f6714d9..745f38c 100644
> --- a/lib/librte_eal/common/eal_options.h
> +++ b/lib/librte_eal/common/eal_options.h
> @@ -63,6 +63,8 @@ enum {
>   	OPT_PROC_TYPE_NUM,
>   #define OPT_NO_HPET           "no-hpet"
>   	OPT_NO_HPET_NUM,
> +#define OPT_HUGE_UNLINK        "huge-unlink"
> +	OPT_HUGE_UNLINK_NUM,
>   #define OPT_NO_HUGE           "no-huge"
>   	OPT_NO_HUGE_NUM,
>   #define OPT_NO_PCI            "no-pci"
> diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
> b/lib/librte_eal/linuxapp/eal/eal_memory.c
> index ac2745e..2b86428 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
> @@ -786,6 +786,37 @@ copy_hugepages_to_shared_mem(struct hugepage_file *
> dst, int dest_size,
>   	return 0;
>   }
>   
> +static int
> +unlink_hugepage_files(struct hugepage_file *hugepg_tbl,
> +		struct hugepage_info *hpi,
> +		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 (size = 0; size < num_hp_info; size++) {
> +		for (socket = 0; socket < RTE_MAX_NUMA_NODES; socket++) {
> +			for (page = 0; page < nrpages; page++) {
> +				struct hugepage_file *hp = &hugepg_tbl[page];
> +				if ((hp->size == hpi[size].hugepage_sz) &&
> +						(hp->socket_id == (int) socket) &&
> +						hp->final_va != NULL) {
Is all this necessary? At this point, all unneeded hugepages have been 
released and their final_va set to NULL.
I think we just need to calculate the total number of hugepages and loop 
through all hugepg_tbl entries checking va_final != NULL, then unlink.

Sergio
> +						if (unlink(hp->filepath)) {
> +							RTE_LOG(WARNING, EAL, "%s(): Removing %s failed: %s\n",
> +								__func__, hp->filepath, strerror(errno));
> +					}
> +				}
> +			} /* foreach page */
> +		} /* foreach socket */
> +	} /* foreach pagesize */
> +	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 +1320,14 @@ rte_eal_hugepage_init(void)
>   		goto fail;
>   	}
>   
> +	/* free the hugepage backing files */
> +	if (internal_config.hugepage_unlink &&
> +		unlink_hugepage_files(tmp_hp, used_hp,
> +			internal_config.num_hugepage_sizes) < 0) {
> +			RTE_LOG(ERR, EAL, "Unlinking hugepage backing files failed!\n");
> +		goto fail;
> +	}
> +
>   	/* free the temporary hugepage table */
>   	free(tmp_hp);
>   	tmp_hp = NULL;