Hi John,
> Before this patch, DPDK used the file ~/.rte_config as a lock to detect
> potential interference between multiple DPDK applications running on the
> same machine. However, if a single user ran DPDK applications concurrently
> on several different machines, and if the user's home directory was shared
> between the machines via NFS, DPDK would incorrectly detect conflicts
> for all but the first application and abort them. This patch fixes the
> problem by incorporating the machine name into the config file name (e.g.,
> ~/.rte_hostname_config).
>
> Signed-off-by: John Ousterhout <ouster at cs.stanford.edu>
> ---
> doc/guides/prog_guide/multi_proc_support.rst | 11 +++++++----
> lib/librte_eal/common/eal_common_proc.c | 8 ++------
> lib/librte_eal/common/eal_filesystem.h | 15 +++++++++++++--
> 3 files changed, 22 insertions(+), 12 deletions(-)
>
> diff --git a/doc/guides/prog_guide/multi_proc_support.rst
> b/doc/guides/prog_guide/multi_proc_support.rst
> index badd102..a54fa1c 100644
> --- a/doc/guides/prog_guide/multi_proc_support.rst
> +++ b/doc/guides/prog_guide/multi_proc_support.rst
> @@ -129,10 +129,13 @@ Support for this usage scenario is provided using the
> ``--file-prefix`` paramete
>
> By default, the EAL creates hugepage files on each hugetlbfs filesystem
> using the rtemap_X filename,
> where X is in the range 0 to the maximum number of hugepages -1.
> -Similarly, it creates shared configuration files, memory mapped in each
> process, using the /var/run/.rte_config filename,
> -when run as root (or $HOME/.rte_config when run as a non-root user;
> -if filesystem and device permissions are set up to allow this).
> -The rte part of the filenames of each of the above is configurable using the
> file-prefix parameter.
> +Similarly, it creates shared configuration files, memory mapped in each
> process.
> +When run as root, the name of the configuration file will be
> +/var/run/.rte_*host*_config, where *host* is the name of the machine.
> +When run as a non-root user, the the name of the configuration file will be
> +$HOME/.rte_*host*_config (if filesystem and device permissions are set up to
> allow this).
> +If the ``--file-prefix`` parameter has been specified, its value will be used
> +in place of "rte" in the file names.
I am not sure that we need to handle all such cases inside EAL.
User can easily overcome that problem by just adding something like:
--file-prefix=`uname -n`
to his command-line.
Konstantin
>
> In addition to specifying the file-prefix parameter,
> any DPDK applications that are to be run side-by-side must explicitly limit
> their memory use.
> diff --git a/lib/librte_eal/common/eal_common_proc.c
> b/lib/librte_eal/common/eal_common_proc.c
> index 12e0fca..517aa0c 100644
> --- a/lib/librte_eal/common/eal_common_proc.c
> +++ b/lib/librte_eal/common/eal_common_proc.c
> @@ -45,12 +45,8 @@ rte_eal_primary_proc_alive(const char *config_file_path)
>
> if (config_file_path)
> config_fd = open(config_file_path, O_RDONLY);
> - else {
> - char default_path[PATH_MAX+1];
> - snprintf(default_path, PATH_MAX, RUNTIME_CONFIG_FMT,
> - default_config_dir, "rte");
> - config_fd = open(default_path, O_RDONLY);
> - }
> + else
> + config_fd = open(eal_runtime_config_path(), O_RDONLY);
> if (config_fd < 0)
> return 0;
>
> diff --git a/lib/librte_eal/common/eal_filesystem.h
> b/lib/librte_eal/common/eal_filesystem.h
> index fdb4a70..4929aa3 100644
> --- a/lib/librte_eal/common/eal_filesystem.h
> +++ b/lib/librte_eal/common/eal_filesystem.h
> @@ -41,7 +41,7 @@
> #define EAL_FILESYSTEM_H
>
> /** Path of rte config file. */
> -#define RUNTIME_CONFIG_FMT "%s/.%s_config"
> +#define RUNTIME_CONFIG_FMT "%s/.%s_%s_config"
>
> #include <stdint.h>
> #include <limits.h>
> @@ -59,11 +59,22 @@ eal_runtime_config_path(void)
> static char buffer[PATH_MAX]; /* static so auto-zeroed */
> const char *directory = default_config_dir;
> const char *home_dir = getenv("HOME");
> + static char nameBuffer[1000];
> + int result;
>
> if (getuid() != 0 && home_dir != NULL)
> directory = home_dir;
> +
> + /*
> + * Include the name of the host in the config file path. Otherwise,
> + * if DPDK applications run on different hosts but share a home
> + * directory (e.g. via NFS), they will choose the same config
> + * file and conflict unnecessarily.
> + */
> + result = gethostname(nameBuffer, sizeof(nameBuffer)-1);
> snprintf(buffer, sizeof(buffer) - 1, RUNTIME_CONFIG_FMT, directory,
> - internal_config.hugefile_prefix);
> + internal_config.hugefile_prefix,
> + (result == 0) ? nameBuffer : "unknown-host");
> return buffer;
> }
>
> --
> 2.8.3
