-----Original Message-----
From: Burakov, Anatoly <anatoly.bura...@intel.com>
Sent: Tuesday, November 5, 2019 11:31 AM
To: David Marchand <david.march...@redhat.com>; Yasufumi Ogawa
<yasufu...@gmail.com>
Cc: Ananyev, Konstantin <konstantin.anan...@intel.com>; dev
<dev@dpdk.org>; dpdk stable <sta...@dpdk.org>; Yasufumi Ogawa
<ogawa.yasuf...@lab.ntt.co.jp>
Subject: Re: [PATCH v6 1/1] fbarray: fix duplicated fbarray file in
secondary
On 05-Nov-19 10:13 AM, David Marchand wrote:
Hello Anatoly, Yasufumi,
On Mon, Nov 4, 2019 at 11:20 AM Burakov, Anatoly
<anatoly.bura...@intel.com> wrote:
On 01-Nov-19 9:04 AM, yasufu...@gmail.com wrote:
From: Yasufumi Ogawa <ogawa.yasuf...@lab.ntt.co.jp>
In secondary_msl_create_walk(), it creates a file for fbarrays
with its
PID for reserving unique name among secondary processes. However, it
does not work if several secondaries run as app containers because
each
of containerized secondary has PID 1, and failed to reserve unique
name
other than first one. To reserve unique name in each of
containers, use
hostname in addition to PID.
Cc: sta...@dpdk.org
We can't backport this as is, see below.
Signed-off-by: Yasufumi Ogawa <yasufu...@gmail.com>
---
lib/librte_eal/common/include/rte_fbarray.h | 2 +-
lib/librte_eal/linux/eal/eal_memalloc.c | 11 ++++++++---
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/lib/librte_eal/common/include/rte_fbarray.h
b/lib/librte_eal/common/include/rte_fbarray.h
index 6dccdbec9..5c2815093 100644
--- a/lib/librte_eal/common/include/rte_fbarray.h
+++ b/lib/librte_eal/common/include/rte_fbarray.h
@@ -39,7 +39,7 @@ extern "C" {
#include <rte_compat.h>
#include <rte_rwlock.h>
-#define RTE_FBARRAY_NAME_LEN 64
+#define RTE_FBARRAY_NAME_LEN NAME_MAX
The change on RTE_FBARRAY_NAME_LEN breaks the ABI, so we cannot
backport this as is.
For 19.11, we can allow this breakage, but we need an update of the
release notes.
OK. I wasn't careful for the ABI change. I think RTE_FBARRAY_NAME_LEN 64
is enough without using hostname as a part of fbarray. So I would like
to discard this change.
Besides, what is the impact in terms of memory consumption?
struct rte_fbarray {
char name[RTE_FBARRAY_NAME_LEN]; /**< name associated with
an array */
diff --git a/lib/librte_eal/linux/eal/eal_memalloc.c
b/lib/librte_eal/linux/eal/eal_memalloc.c
index af6d0d023..24f0275c9 100644
--- a/lib/librte_eal/linux/eal/eal_memalloc.c
+++ b/lib/librte_eal/linux/eal/eal_memalloc.c
@@ -1365,6 +1365,7 @@ secondary_msl_create_walk(const struct
rte_memseg_list *msl,
struct rte_memseg_list *primary_msl, *local_msl;
char name[PATH_MAX];
int msl_idx, ret;
+ char hostname[HOST_NAME_MAX] = { 0 };
if (msl->external)
return 0;
@@ -1373,9 +1374,13 @@ secondary_msl_create_walk(const struct
rte_memseg_list *msl,
primary_msl = &mcfg->memsegs[msl_idx];
local_msl = &local_memsegs[msl_idx];
- /* create distinct fbarrays for each secondary */
- snprintf(name, RTE_FBARRAY_NAME_LEN, "%s_%i",
- primary_msl->memseg_arr.name, getpid());
+ /* Create distinct fbarrays for each secondary by using PID and
+ * hostname. The reason why using hostname is because PID
could be
+ * duplicated among secondaries if it is launched in a
container.
+ */
+ gethostname(hostname, HOST_NAME_MAX);
Personal preference, s/HOST_NAME_MAX/sizeof(hostname)/.
hostname[] is HOST_NAME_MAX bytes long.
In the worst case, we can get a non NULL terminated hostname string.
"
gethostname() returns the null-terminated hostname in the
character array name, which has a length of len bytes. If the
null-terminated hostname is too large to fit, then the name is
truncated, and
no error is returned (but see NOTES below). POSIX.1-2001 says
that if such truncation occurs, then it is unspecified whether the
returned buffer includes a terminating null byte.
...
NOTES
SUSv2 guarantees that "Host names are limited to 255 bytes".
POSIX.1-2001 guarantees that "Host names (not including the
terminating null byte) are limited to HOST_NAME_MAX bytes". On
Linux,
HOST_NAME_MAX is defined with the value 64, which has been the
limit since Linux 1.0 (earlier kernels imposed a limit of 8 bytes).
"
How about making hostname[] HOST_NAME_MAX+1 bytes long?
+ snprintf(name, RTE_FBARRAY_NAME_LEN, "%s_%s_%d",
+ primary_msl->memseg_arr.name, hostname,
(int)getpid());
ret = rte_fbarray_init(&local_msl->memseg_arr, name,
primary_msl->memseg_arr.len,
I think the order should be reversed. Both containers and
non-containers
can have their hostname set, and RTE_FBARRAY_NAME_LEN is of fairly
limited length, so if the hostname is long enough, the PID never gets
into the name string, resulting in duplicates. It is better have
pid first.
Anatoly,
On the principle, it seems better, yes.
Just the comment on RTE_FBARRAY_NAME_LEN indicates that you missed the
change at the top of the patch.
What do you think of this change?
Yes, i did miss that, apologies.
I don't have a strong opinion on this change, however the above comment
would still be true if we make fbarray size to be hostname_max + 1 - we
still potentially get no space for a pid. So if we're going to have pid
in there as well, it should be hostname_max + pid_max (5 digits?) +
whatever underscores we have + null terminator, to ensure it fits under
any and all circumstances.#
In "man 5 proc", it says the default value of pid_max is 32768, but can
be set up to 2^22 (=4194304) on 64-bit systems. So, I think it is safer
to consider pid_max is 7 digits.
I can find secondary's fbarray file named as
$ sudo ls /var/run/dpdk/rte/
...
fbarray_memseg-1048576k-0-0_24118
fbarray_memseg-1048576k-0-0_24191
fbarray_memseg-1048576k-0-0_24199
...
It consists of [prefix]-[hugepage size]-[numa node?]-[memchan?]_[PID]",
and size of the name before PID is totally 28 digits. If another
underscore and hostname are included in the name, the max size of
fbarray file name is
28 + 7(PID) + 1(underscore) + HOST_NAME_MAX+1(null terminator)
Considering 28 can be larger, how about using 32 as following?
+ int fbarray_sec_name_len = 32 + 7 + 1 + HOST_NAME_MAX + 1;
+ snprintf(name, fbarray_sec_name_len, "%s_%d_%s",
+ primary_msl->memseg_arr.name, getpid(), hostname);
I think that at least on linux we have more than enough space here:
$ find /usr/include -type f | xargs grep ' NAME_MAX' | grep define
/usr/include/linux/limits.h:#define NAME_MAX 255 /* #
chars in a file name */
$ find /usr/include -type f | xargs grep ' HOST_NAME_MAX' | grep define
/usr/include/i386-linux-gnu/bits/local_lim.h:#define
HOST_NAME_MAX 64
/usr/include/x86_64-linux-gnu/bits/local_lim.h:#define
HOST_NAME_MAX 64
Okay, works for me :)
Thanks,
Yasufumi
