[CRIU] [PATCH v2 resent 1/4] ipc/sysctl: c/r fs.mqueue.msg_default fs.mqueue.msgsize_default

[Pavel Tikhomirov]

On 07/13/2016 03:58 PM, Pavel Tikhomirov wrote:
>
>
> On 07/13/2016 03:52 PM, Pavel Emelyanov wrote:
>> On 07/04/2016 10:47 AM, Pavel Tikhomirov wrote:
>>> we already have 3/5 fs.mqueue.xxx sysctls so why not have all:
>>>
>>> /proc/sys/fs/mqueue/msg_default is  a read/write  file for
>>> setting/getting the default number of messages in a queue value
>>> if attr parameter of mq_open(2) is NULL. If it exceed msg_max,
>>> the default value is initialized msg_max.
>>>
>>> /proc/sys/fs/mqueue/msgsize_default is a read/write file for
>>> setting/getting the default message size value if attr parameter
>>> of mq_open(2) is NULL. If it exceed msgsize_max, the default
>>> value is initialized msgsize_max.
>>>
>>> *We have these sysctls writable in VZ7 CT.
>>
>> What about upstream kernel? Are these writable for it as well? If yes,
>> how
>> has it happened that vzkernel DIDN'T have them as such at some point?
>

Sorry, I though it was about net sysctls but that is about ipc...

So, for ipc sysctls:

Sysctls are writable in sub-ipcns:
# unshare -ri
# cat /proc/sys/fs/mqueue/msgsize_default
8192
# echo 16384 > /proc/sys/fs/mqueue/msgsize_default
# cat /proc/sys/fs/mqueue/msgsize_default
16384

Sysctls msg(size)_default become writable in vzkernel in commit:

commit 42faae2077ff33775d612b0d4f17aedc000e0a37
Author: Andrew Vagin <avagin at openvz.org>
Date:   Thu Dec 19 13:28:27 2013 +0400

     ve/sysctl: allow to change mqueue sysctl-s

     All mqueue data are accounted into the kmem ubc.
     These sysctl belong to ipcns, so all changes doesn't affect other 
containers.

     https://jira.sw.ru/browse/PSBM-20102

     Signed-off-by: Andrew Vagin <avagin at openvz.org>
     Acked-by: Cyrill Gorcunov <gorcunov at openvz.org>

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.