Re: [PATCH v2 00/31] Replacing net_mutex with rw_semaphore

[Kirill Tkhai <ktkhai@virtuozzo.com>]

On 18.01.2018 20:43, Andrei Vagin wrote:
> On Mon, Nov 20, 2017 at 09:32:08PM +0300, Kirill Tkhai wrote:
>> Hi,
>>
>> there is the second version of patchset introducing net_sem
>> instead of net_mutex. The patchset adds net_sem in addition
>> to net_mutex and allows pernet_operations to be async. This
>> flag means, the pernet_operations methods are safe to be
>> executed with any othor pernet_operations (un)initializing
>> another net.
>>
>> If there are only async pernet_operations in the system,
>> net_mutex is not used either for setup_net() or for cleanup_net().
>>
>> The flag is little easier, then (un)register_pernet_sys(),
>> as it changes one line only. Also, it requires less changes
>> in code. In future, when all pernet_operations are async,
>> we'll just remove this struct field.
>>
>> The pernet_operations converted in this patchset allow
>> to create minimal .config to have network working, and
>> the changes improve the performance like you may see
>> below:
>>
>>     %for i in {1..10000}; do unshare -n bash -c exit; done
>>     
>>     *before*
>>     real 1m40,377s
>>     user 0m9,672s
>>     sys 0m19,928s
>>     
>>     *after*
>>     real 0m17,007s
>>     user 0m5,311s
>>     sys 0m11,779
>>     
>>     (5.8 times faster)
> 
> Good job!
> 
> Acked-by: Andrei Vagin <avagin@virtuozzo.com>

Thanks, Andrei!

>> ---
>>
>> Kirill Tkhai (31):
>>       net: Assign net to net_namespace_list in setup_net()
>>       net: Cleanup copy_net_ns()
>>       net: Introduce net_sem for protection of pernet_list
>>       net: Move mutex_unlock() in cleanup_net() up
>>       net: Allow pernet_operations to be executed in parallel
>>       net: Convert proc_net_ns_ops
>>       net: Convert net_ns_ops methods
>>       net: Convert sysctl_pernet_ops
>>       net: Convert netfilter_net_ops
>>       net: Convert nf_log_net_ops
>>       net: Convert net_inuse_ops
>>       net: Convert net_defaults_ops
>>       net: Convert netlink_net_ops
>>       net: Convert rtnetlink_net_ops
>>       net: Convert audit_net_ops
>>       net: Convert uevent_net_ops
>>       net: Convert proto_net_ops
>>       net: Convert pernet_subsys ops, registered via net_dev_init()
>>       net: Convert fib_* pernet_operations, registered via subsys_initcall
>>       net: Convert subsys_initcall() registered pernet_operations from net/sched
>>       net: Convert genl_pernet_ops
>>       net: Convert wext_pernet_ops
>>       net: Convert sysctl_core_ops
>>       net: Convert pernet_subsys, registered from inet_init()
>>       net: Convert unix_net_ops
>>       net: Convert packet_net_ops
>>       net: Convert ipv4_sysctl_ops
>>       net: Convert addrconf_ops
>>       net: Convert loopback_net_ops
>>       net: Convert default_device_ops
>>       net: Convert diag_net_ops
>>
>>
>>  drivers/net/loopback.c      |    1 
>>  fs/proc/proc_net.c          |    1 
>>  include/linux/rtnetlink.h   |    1 
>>  include/net/net_namespace.h |    6 +++
>>  kernel/audit.c              |    1 
>>  lib/kobject_uevent.c        |    1 
>>  net/core/dev.c              |    2 +
>>  net/core/fib_notifier.c     |    1 
>>  net/core/fib_rules.c        |    1 
>>  net/core/net-procfs.c       |    2 +
>>  net/core/net_namespace.c    |   94 +++++++++++++++++++++++++------------------
>>  net/core/rtnetlink.c        |    5 +-
>>  net/core/sock.c             |    2 +
>>  net/core/sock_diag.c        |    1 
>>  net/core/sysctl_net_core.c  |    1 
>>  net/ipv4/af_inet.c          |    2 +
>>  net/ipv4/arp.c              |    1 
>>  net/ipv4/devinet.c          |    1 
>>  net/ipv4/fib_frontend.c     |    1 
>>  net/ipv4/icmp.c             |    1 
>>  net/ipv4/igmp.c             |    1 
>>  net/ipv4/ip_fragment.c      |    1 
>>  net/ipv4/ipmr.c             |    1 
>>  net/ipv4/ping.c             |    1 
>>  net/ipv4/proc.c             |    1 
>>  net/ipv4/raw.c              |    1 
>>  net/ipv4/route.c            |    4 ++
>>  net/ipv4/sysctl_net_ipv4.c  |    1 
>>  net/ipv4/tcp_ipv4.c         |    2 +
>>  net/ipv4/tcp_metrics.c      |    1 
>>  net/ipv4/udp.c              |    1 
>>  net/ipv4/udplite.c          |    1 
>>  net/ipv4/xfrm4_policy.c     |    1 
>>  net/ipv6/addrconf.c         |    1 
>>  net/netfilter/core.c        |    1 
>>  net/netfilter/nf_log.c      |    1 
>>  net/netlink/af_netlink.c    |    1 
>>  net/netlink/genetlink.c     |    1 
>>  net/packet/af_packet.c      |    1 
>>  net/sched/act_api.c         |    1 
>>  net/sched/sch_api.c         |    1 
>>  net/sysctl_net.c            |    1 
>>  net/unix/af_unix.c          |    1 
>>  net/wireless/wext-core.c    |    1 
>>  net/xfrm/xfrm_policy.c      |    1 
>>  45 files changed, 114 insertions(+), 41 deletions(-)
>>
>> --
>> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>