Re: [PATCH v2 net-next 0/3] netem: use a seeded PRNG for loss and corruption events

[Simon Horman]

On Tue, Aug 15, 2023 at 11:23:37AM +0200, Francois Michel wrote:
> From: François Michel <francois.michel@xxxxxxxxxxxx>
> 
> In order to reproduce bugs or performance evaluation of
> network protocols and applications, it is useful to have
> reproducible test suites and tools. This patch adds
> a way to specify a PRNG seed through the
> TCA_NETEM_PRNG_SEED attribute for generating netem
> loss and corruption events. Initializing the qdisc
> with the same seed leads to the exact same loss
> and corruption patterns. If no seed is explicitly
> specified, the qdisc generates a random seed using
> get_random_u64().
> 
> This patch can be and has been tested using tc from
> the following iproute2-next fork:
> https://github.com/francoismichel/iproute2-next
> 
> For instance, setting the seed 42424242 on the loopback
> with a loss rate of 10% will systematically drop the 5th,
> 12th and 24th packet when sending 25 packets.
> 
> v1 -> v2: Address comments and directly use
> prandom_u32_state() instead of get_random_u32() for
> generating loss and corruption events. Generates a random
> seed using get_random_u64() if none was provided explicitly.
> 
> François Michel (3):
>   netem: add prng attribute to netem_sched_data
>   netem: use a seeded PRNG for generating random losses
>   netem: use seeded PRNG for correlated loss events
> 
>  include/uapi/linux/pkt_sched.h |  1 +
>  net/sched/sch_netem.c          | 49 +++++++++++++++++++++++-----------
>  2 files changed, 35 insertions(+), 15 deletions(-)

For series,

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>