2009-07-13 15:44:34     read, write system calls slow with BF533 0.4, 0.3 silicon rev.

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2009-07-13 15:44:34     read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Amol Sukerkar (UNITED STATES)

Message: 77145   

 

Hello,

 

            I am developing an application that executes a process using execve call and talks to it using Inter Process Communication pipes. I have noticed that the read and write system calls respond slowly and take as much as 1 - 2 seconds to return on 0.4 and 0.3 silicon versions of BF533. It works just fine without any delay with silicon version 0.5. This looks as a hardware issue. Is this a known issue? If it is, then, is there a workaround associated with it? Any help would be appreciated.

 

Information

 

Platform: BF533 (0.3, 0.4, 0.5)

 

Filesystem: Blackfin uClinux (Kernel Version: 2.4.8 antique?)

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2009-07-13 16:23:39     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Robin Getz (UNITED STATES)

Message: 77146   

 

Amol:

 

Update your kernel. Are you really using 2.4?

 

-Robin

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2009-07-13 19:49:44     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Amol Sukerkar (UNITED STATES)

Message: 77149   

 

Thanks, Robin! I wish it was in my capacity to update the kernel (I would have done it years ago). Anyways, the reason I was baffled about this was because the read, write work fine with 0.5 silicon revision and not with 0.3 or 0.4 silicon revisions. So, could this be a hardware issue and not kernel issue? I was wondering if the uClinux maintainers were aware of this issue and had any pointers for me to look in the right direction.

 

- Amol

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2009-07-14 00:09:51     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Mike Frysinger (UNITED STATES)

Message: 77153   

 

linux-2.4 has never come from us.  we have no idea what's going on with it.

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2009-07-14 08:14:28     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Robin Getz (UNITED STATES)

Message: 77213   

 

Amol:

 

It is likely that you are running into an anomaly that existing on 0.3 and 0.4, but not on 0.5 - consider yourself luckly that things work at all.

 

Please let me know what product this is in - so I can know not to buy it. the 2.4 kernel is not safe to use.

 

-Robin

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2009-07-14 11:25:36     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Amol Sukerkar (UNITED STATES)

Message: 77235   

 

That was very helpful. I am quiet sure it is a silicon anomaly and nothing to do with linux kernel, hence, I decided to post on the forum. Apart from this, I don't have any comments. I'll go to the gym instead.

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2009-07-14 11:30:08     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Mike Frysinger (UNITED STATES)

Message: 77238   

 

you're asking about a code base that has never come from us, that we've never seen, and that we have no idea about.  basically, with linux-2.4, you're completely on your own.  or go bug the people who gave you the source code in the first place.

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2009-07-14 12:33:03     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Amol Sukerkar (UNITED STATES)

Message: 77248   

 

Mike,

 

          This is a misunderstanding. I am not talking about source code at all. I've been posting about my crappy 2.4 code for quiet some time now and get the same answer. Upgrade to 2.6. I posted this to find out if this hardware anomaly is known to the maintainers of uClinux.

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2009-07-14 12:43:38     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Mike Frysinger (UNITED STATES)

Message: 77251   

 

there is no way to even guess at what is going wrong in your system.  read()/write() functions do not directly touch the hardware in anyway.

 

you keep getting the same answer because 2.4 is different from 2.6 in pretty much everything

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2009-07-14 17:33:37     Re: read, write system calls slow with BF533 0.4, 0.3 silicon rev.

Robin Getz (UNITED STATES)

Message: 77263   

 

Amol:

 

So - why would you expect a different answer?

 

As far as I know -- there were zero anomaly workarounds included in the 2.4 kernel. If you want to look out for things - check out the anomaly list:

 

https://docs.blackfin.uclinux.org/doku.php?id=bfin:anomalies

 

Your kernel will have zero workarounds - unless you added them.

 

It also just plain did not work well.

 

-Robin

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