[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 2 Feb 2015 11:27:15 +0100
From: Michal Kazior <michal.kazior@...to.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: linux-wireless <linux-wireless@...r.kernel.org>,
Network Development <netdev@...r.kernel.org>,
eyalpe@....mellanox.co.il
Subject: Re: Throughput regression with `tcp: refine TSO autosizing`
On 30 January 2015 at 15:40, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Fri, 2015-01-30 at 14:39 +0100, Michal Kazior wrote:
>
>> I've briefly tried playing with this knob to no avail unfortunately. I
>> tried 256K, 1M - it didn't improve TCP performance. When I tried to
>> make it smaller (e.g. 16K) the traffic dropped even more so it does
>> have an effect. It seems there's some other limiting factor in this
>> case.
>
> Interesting.
>
> Could you take some tcpdump/pcap with various tcp_limit_output_bytes
> values ?
>
> echo 131072 >/proc/sys/net/ipv4/tcp_limit_output_bytes
> tcpdump -p -i wlanX -s 128 -c 20000 -w 128k.pcap
>
> echo 262144 >/proc/sys/net/ipv4/tcp_limit_output_bytes
> tcpdump -p -i wlanX -s 128 -c 20000 -w 256k.pcap
I've run a couple of tests across different kernels. This got pretty
big so I decided to use an external file hosting:
http://www.filedropper.com/testtar
Let me know if you can't access it (and perhaps you could suggest how
you prefer the logs to be delivered in that case).
The layout of logs is: $kernel/$limit-P$threads.pcap. I've also
included the test script and output of each test run.
While testing I've had my internal GRO patch for ath10k and no stretch
ack patches.
When I was trying to come up with a testing methodology I've noticed
something interesting:
1. set 16k limit
2. start iperf -P1
3. observe 200mbps
4. set 2048k limit (while iperf is running)
5. observe 600mbps
6. set 16limit back (while iperf is running)
7. observe 500-600mbps (i.e. no drop to 200mbps)
Due to that I've decided to re-start iperf for each limit test.
If you want me to gather some other logs/dumps/configuration
permutations let me know, please.
MichaĆ
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists