RE: [microblaze-uclinux] Patch for stability under heavy IRQ load

[Brettschneider Falk <fbrettschneider@xxxxxxxxxxxxxxxxx>]

Hi,

Alejandro Lucero wrote:
> I did the RTLinux port to microblaze/uClinux. It works but 
> under some heavy 
> tests system crashes. The testbench is:
> 
> 	- 500us periodic RT task
> 	- ping flood from another machine
> 	- endless shell script doing some 'ls -l' commands on a 
> NFS mounted directory
> 
> I'm using the addresses 0x1000 to 0x4000 (related with LMB 
> and not used by 
> uClinux) to log system calls entries, system calls exits and context 
> switches. The entry.S file has been modified to do it and to 
> check some 
> erroneous values as a system call number greater then 250 
> which will stop the 
> machine. A counter tells me where was the address of the last 
> entry and then 
> I can know what was the last thing done by the OS. After a 
> lot of tests I 
> know this is always after a sys_execve and it shows the 
> system call returns 
> to the address of the brki instruction of previous process 
> frame (destroyed 
> during the normal execve work). The problem is I don't know 
> if this is the 
> point (I have re-read carefully the code and I cant see any 
> track) or this 
> situation is created from a previous error on vfork.
> 
> I have not a lot of time to work on this, so I use some time 
> during the nights 
> but it is not enough until now.
> 
> I think at this point this could be more a problem of the 
> RTLinux port instead 
> of a uClinux one, but if there's someone with the same 
> problems and without 
> RTlinux working, then things change. 
> 
> Is it the case for you?
Unfortunately, I don't have TCP. So I'm not able to try to reproduce your
special scenario.
Concerning your RTLinux patch: This sounds very interesting. Is it public
somehow? Do you have a faster OS response with it now? Here, the time from
IRQ to user app reaction is about 600µs which is quite slow, and I'm very
interested in improving it.

Cheers,
F@lk

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