Re: [dpdk-dev] [PATCH 2/4] mem: add API to obstain memory-backed file info

[Pavel Fedin <p.fedin@samsung.com>]

 Hello!

> -----Original Message-----
> From: Jianfeng Tan [mailto:jianfeng.tan@intel.com]
> Sent: Sunday, January 10, 2016 2:43 PM
> To: dev@dpdk.org
> Cc: rich.lane@bigswitch.com; yuanhan.liu@linux.intel.com; mst@redhat.com;
> nakajima.yoshihiro@lab.ntt.co.jp; huawei.xie@intel.com; mukawa@igel.co.jp;
> p.fedin@samsung.com; michael.qiu@intel.com; ann.zhuangyanying@huawei.com; Jianfeng Tan
> Subject: [PATCH 2/4] mem: add API to obstain memory-backed file info

 "obtain" - typo in subject

> 
> A new API named rte_eal_get_backfile_info() and a new data
> struct back_file is added to obstain information of memory-
> backed file info.
> 
> Signed-off-by: Huawei Xie <huawei.xie@intel.com>
> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> ---
>  lib/librte_eal/common/include/rte_memory.h | 16 +++++++++++++
>  lib/librte_eal/linuxapp/eal/eal_memory.c   | 37 ++++++++++++++++++++++++++++++
>  2 files changed, 53 insertions(+)
> 
> diff --git a/lib/librte_eal/common/include/rte_memory.h
> b/lib/librte_eal/common/include/rte_memory.h
> index 9c9e40f..75ef8db 100644
> --- a/lib/librte_eal/common/include/rte_memory.h
> +++ b/lib/librte_eal/common/include/rte_memory.h
> @@ -109,6 +109,22 @@ struct rte_memseg {
>  } __rte_packed;
> 
>  /**
> + * This struct is used to store information about memory-backed file that
> + * we mapped in memory initialization.
> + */
> +struct back_file {
> +	void *addr;         /**< virtual addr */
> +	size_t size;        /**< the page size */
> +	char filepath[PATH_MAX]; /**< path to backing file on filesystem */
> +};
> +
> +/**
> +  * Get the hugepage file information. Caller to free.
> +  * Return number of hugepage files used.
> +  */
> +int rte_eal_get_backfile_info(struct back_file **);
> +
> +/**
>   * Lock page in physical memory and prevent from swapping.
>   *
>   * @param virt
> diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
> b/lib/librte_eal/linuxapp/eal/eal_memory.c
> index 2bb1163..6ca1404 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
> @@ -758,6 +758,9 @@ sort_by_physaddr(struct hugepage_file *hugepg_tbl, struct hugepage_info
> *hpi)
>  	return 0;
>  }
> 
> +static struct hugepage_file *hugepage_files;
> +static int num_hugepage_files;
> +
>  /*
>   * Uses mmap to create a shared memory area for storage of data
>   * Used in this file to store the hugepage file map on disk
> @@ -776,9 +779,29 @@ create_shared_memory(const char *filename, const size_t mem_size)
>  	retval = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
>  	close(fd);
> 
> +	hugepage_files = retval;
> +	num_hugepage_files = mem_size / (sizeof(struct hugepage_file));
> +
>  	return retval;
>  }
> 
> +int
> +rte_eal_get_backfile_info(struct back_file **p)
> +{
> +	struct back_file *backfiles;
> +	int i, num_backfiles = num_hugepage_files;
> +
> +	backfiles = malloc(sizeof(struct back_file) * num_backfiles);
> +	for (i = 0; i < num_backfiles; ++i) {
> +		backfiles[i].addr = hugepage_files[i].final_va;
> +		backfiles[i].size = hugepage_files[i].size;
> +		strcpy(backfiles[i].filepath, hugepage_files[i].filepath);
> +	}
> +
> +	*p = backfiles;
> +	return num_backfiles;
> +}
> +
>  /*
>   * this copies *active* hugepages from one hugepage table to another.
>   * destination is typically the shared memory.
> @@ -1157,6 +1180,20 @@ rte_eal_hugepage_init(void)
>  		mcfg->memseg[0].len = internal_config.memory;
>  		mcfg->memseg[0].socket_id = socket_id;
> 
> +		hugepage = create_shared_memory(eal_hugepage_info_path(),
> +				sizeof(struct hugepage_file));
> +		hugepage->orig_va = addr;
> +		hugepage->final_va = addr;
> +		hugepage->physaddr = rte_mem_virt2phy(addr);
> +		hugepage->size = pagesize;
> +		hugepage->socket_id = socket_id;
> +		hugepage->file_id = 0;
> +		hugepage->memseg_id = 0;
> +#ifdef RTE_EAL_SINGLE_FILE_SEGMENTS
> +		hugepage->repeated = internal_config.memory / pagesize;
> +#endif
> +		strncpy(hugepage->filepath, filepath, MAX_HUGEPAGE_PATH);
> +
>  		close(fd);
> 
>  		return 0;
> --
> 2.1.4

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia