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Re: [lwip-users] Delayed ACKs
From: |
Kaufman, Michael |
Subject: |
Re: [lwip-users] Delayed ACKs |
Date: |
Mon, 1 Feb 2016 13:05:28 +0000 |
Sergio,
Thanks a lot!
-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Sergio R. Caprile
Sent: Monday, February 01, 2016 2:58 PM
To: address@hidden
Subject: Re: [lwip-users] Delayed ACKs
> There are restrictions on threading, and that depends on the API you
> use, and if you use NO_SYS=0 or =1.
lwIP is single-threaded, you can't call the RAW API functions from the main
loop and an interrupt handler. Some functions are safe, but the general rule is
to avoid the easy shortcut of pushing incoming frames from the Eth chip handler.
The socket API and the netconn API do not present this restriction (and that is
all I know about them).
Since you have NO_SYS=0 and an OS, you should check how your OS amd your port
handle the polling and frame extraction from the Eth chip. I didn't really dig
into your problem but since you report problems at low delay multiframe input,
that looks consistent with the typical problem:
a frame arrives
the chip signals a frame has arrived
the OS fires a task to poll the chip
the task extracts the frame out
however, if another frame comes in before the first one is extracted, the chip
might not signal for a new frame arrival, since it already has one.
The driver must extract all frames inside the chip, and many driver writers do
not do this.
a frame arrives
the chip signals a frame has arrived
the OS fires a task to poll the chip
another frame arrives
the task extracts the first frame out
the second frame stays there until a third frame arrives, one of the frames
can be lost or overwritten.
Search the list on this subject, there are some examples on this bug. It may or
not apply to your problem, but my best guess is to start digging there.
--
Sergio R. Caprile, Human Being, Bs.As., Argentina
http://www.scaprile.ldir.com.ar/
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