* [Xenomai] Slow Sockets and Pipes with POSIX Skin
@ 2013-10-21 21:41 Neil T. Dantam
2013-10-21 21:49 ` Gilles Chanteperdrix
0 siblings, 1 reply; 2+ messages in thread
From: Neil T. Dantam @ 2013-10-21 21:41 UTC (permalink / raw)
To: xenomai
I am seeing some surprisingly high latencies for socket and pipe
communication using Xenomai's POSIX skin. Pipes, localhost TCP/UDP,
and local domain sockets all show worst case latency of ~100us on
Xenomai 2.6.2.1/Linux 3.4.6 on a Xeon E3-1270v2. Average and 99%
latency is under 20us. Running `xeno-test latency` gives worst-case
latency of ~10us. POSIX message queues have worst case latency below
20us.
I've done the following to reduce latency:
* Disabled CPU frequency scaling
* Disabled USB
* Set real-time scheduling priority
* Prefaulted the stack
The 100us delay seems like what one get from a System Management
Interrupt (SMI). However, since `xeno-test latency` and message
queues both show low latency, it seems unlikely that this could be the
issue.
Has anyone else encountered (or not encountered) similar performance
issues with pipes and sockets?
Cheers,
-ntd
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Xenomai] Slow Sockets and Pipes with POSIX Skin
2013-10-21 21:41 [Xenomai] Slow Sockets and Pipes with POSIX Skin Neil T. Dantam
@ 2013-10-21 21:49 ` Gilles Chanteperdrix
0 siblings, 0 replies; 2+ messages in thread
From: Gilles Chanteperdrix @ 2013-10-21 21:49 UTC (permalink / raw)
To: Neil T. Dantam; +Cc: xenomai
On 10/21/2013 11:41 PM, Neil T. Dantam wrote:
> I am seeing some surprisingly high latencies for socket and pipe
> communication using Xenomai's POSIX skin. Pipes, localhost TCP/UDP,
> and local domain sockets all show worst case latency of ~100us on
> Xenomai 2.6.2.1/Linux 3.4.6 on a Xeon E3-1270v2. Average and 99%
> latency is under 20us. Running `xeno-test latency` gives worst-case
> latency of ~10us. POSIX message queues have worst case latency below
> 20us.
>
> I've done the following to reduce latency:
>
> * Disabled CPU frequency scaling
> * Disabled USB
> * Set real-time scheduling priority
> * Prefaulted the stack
>
> The 100us delay seems like what one get from a System Management
> Interrupt (SMI). However, since `xeno-test latency` and message
> queues both show low latency, it seems unlikely that this could be the
> issue.
>
> Has anyone else encountered (or not encountered) similar performance
> issues with pipes and sockets?
Xenomai posix skin does not handle pipes, and only handles TCP/IP
sockets if you have installed and configured rtnet.
--
Gilles.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2013-10-21 21:41 [Xenomai] Slow Sockets and Pipes with POSIX Skin Neil T. Dantam
2013-10-21 21:49 ` Gilles Chanteperdrix
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