netdev - [patch iproute2 v4 0/3] tc: Add -bs option to batch mode

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Message-Id: <20180102142804.27145-1-chrism@mellanox.com>
Date:   Tue,  2 Jan 2018 23:28:01 +0900
From:   Chris Mi <chrism@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     gerlitz.or@...il.com, stephen@...workplumber.org,
        dsahern@...il.com, marcelo.leitner@...il.com,
        Chris Mi <chrism@...lanox.com>
Subject: [patch iproute2 v4 0/3] tc: Add -bs option to batch mode

Currently in tc batch mode, only one command is read from the batch
file and sent to kernel to process. With this patchset, we can
accumulate
several commands before sending to kernel. The batch size is specified
using option -bs or -batchsize.

To accumulate the commands in tc, client should allocate an array of
struct iovec. If batchsize is bigger than 1, only after the client
has accumulated enough commands, can the client call rtnl_talk_msg
to send the message that includes the iov array. One exception is
that there is no more command in the batch file.

But please note that kernel still processes the requests one by one.
To process the requests in parallel in kernel is another effort.
The time we're saving in this patchset is the user mode and kernel mode
context switch. So this patchset works on top of the current kernel.

Using the following script in kernel, we can generate 1,000,000 rules.
        tools/testing/selftests/tc-testing/tdc_batch.py

Without this patchset, 'tc -b $file' exection time is:

real    0m15.125s
user    0m6.982s
sys     0m8.080s

With this patchset, 'tc -b $file -bs 10' exection time is:

real    0m12.772s
user    0m5.984s
sys     0m6.723s

The insertion rate is improved more than 10%.

In this patchset, we still ack for every rule. If we don't ack at all,

'tc -b $file' exection time is:

real    0m14.484s
user    0m6.919s
sys     0m7.498s

'tc -b $file -bs 10' exection time is:

real    0m11.664s
user    0m6.017s
sys     0m5.578s

We can see that the performance win is to send multiple messages instead
of no acking. I think that's because in tc, we don't spend too much time
processing the ack message.

v3
==
1. Instead of hacking function rtnl_talk directly, add a new function
   rtnl_talk_msg.
2. remove most of global variables to use parameter passing
3. divide the previous patch into 4 patches.

v4
==
1. Remove function setcmdlinetotal. Now in function batch, we read one
   more line to determine if we are reaching the end of file.
2. Remove function __rtnl_check_ack. Now __rtnl_talk calls __rtnl_talk_msg
   directly.
3. if (batch_size < 1)
	batch_size = 1;

Chris Mi (3):
  lib/libnetlink: Add a function rtnl_talk_msg
  tc: Add -bs option to batch mode
  man: Add -bs option to tc manpage

 include/libnetlink.h |   3 ++
 lib/libnetlink.c     |  59 ++++++++++++++++++-------
 man/man8/tc.8        |   5 +++
 tc/m_action.c        |  90 +++++++++++++++++++++++++++++---------
 tc/tc.c              |  69 +++++++++++++++++++++++------
 tc/tc_common.h       |   8 +++-
 tc/tc_filter.c       | 121 +++++++++++++++++++++++++++++++++++++--------------
 7 files changed, 271 insertions(+), 84 deletions(-)

-- 
2.14.3