Le 10/12/2017 à 21:33, Ran Shalit a écrit :
On Sun, Dec 10, 2017 at 5:58 PM, Peter C. Wallace <pcw@xxxxxxxxxxx> wrote:
On Sun, 10 Dec 2017, Ran Shalit wrote:
Date: Sun, 10 Dec 2017 17:40:27 +0200
From: Ran Shalit <ranshalit@xxxxxxxxx>
To: linux-rt-users <linux-rt-users@xxxxxxxxxxxxxxx>
Subject: Ethernet chunks behavior
Hello,
We use rt patch with UBUNTU,and have a "high priority" thread with 1
millisecond periodic rate.
That rt thread, also send UDP Ethernet packets.
This project was ported from VXWORKS project, but we notice the
following difference:
Although the rt thread gets its 1 millisecond periodic in high
accuracy, the udp is being send in chunks, as if several messages are
aggregated before being delivered.
Is there any reason for such behavior ?
Hi,
It's interesting, but I have a question, in linux-rt is it possible to
have realtime in ethernet drivers ? I mean the message are sent
immediately when I write it . This would imply not using NAPI
implementation in drivers
Regards,
S.Ancelot
Regards,
Ran
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Is it possible your Ethernet driver has coalesce options enabled?
Check with ethtool -c devname
Hi,
I will check this tomorrow and update,
I also see that there are other methods for reducing lateny,
In the following guide chapter 12:
https://access.redhat.com/sites/default/files/attachments/201501-perf-brief-low-latency-tuning-rhel7-v1.1.pdf
such as irqbalance,
and there is also some tunning such as
sysctl -w net.ipv4.tcp_low_latency=1
Regards,
Ran
Peter Wallace
Mesa Electronics
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