[ovs-dev] [HELP] Question about userspace meter

Ben Pfaff blp at ovn.org
Wed Oct 30 17:26:33 UTC 2019


On Wed, Oct 30, 2019 at 11:30:48AM +0800, txfh2007 wrote:
>     I have been testing OVS-DPDK Rate limit using meter table these days, but I have found the rate deviation is larger than kernel meter. My test result is as below:

You didn't mention an OVS version number or commit number.  It might be
important to make sure that the following commit is part of whatever
you're testing.

commit 42697ca7757b594cc841d944e43ffc17905e3188
Author: William Tu <u9012063 at gmail.com>
Date:   Fri Apr 19 15:26:41 2019 -0700

    dpif-netdev: fix meter at high packet rate.
    
    When testing packet rate around 1Mpps with meter enabled, the frequency
    of hitting meter action becomes much higher, around 30us each time.
    As a result, the meter's calculation of 'uint32_t delta_t' becomes
    always 0 and meter action has no effect.  This is due to the previous
    commit 05f9e707e194 divides the delta by 1000, in order to convert to
    msec granularity.  The patch fixes it updating the time when across
    millisecond boundary.
    
    Fixes: 05f9e707e194 ("dpif-netdev: Use microsecond granularity.")
    Acked-by: Yi-Hung Wei <yihung.wei at gmail.com>
    Acked-by: Ilya Maximets <i.maximets at samsung.com>
    Signed-off-by: William Tu <u9012063 at gmail.com>
    Signed-off-by: Ben Pfaff <blp at ovn.org>


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