Re: 2.5.69 Interrupt Latency

[Brian Gerst]

Paul Fulghum wrote:
> On Thu, 2003-05-08 at 14:22, Andrew Morton wrote:
> 
>>Paul Fulghum <[e-mail]> wrote:
>>
>>>On Wed, 2003-05-07 at 17:28, Andrew Morton wrote:
>>>
>>>>Paul Fulghum <[e-mail]> wrote:
>>>>
>>>>>2.5.69
>>>>>Latency 100-110usec (5x increase)
>>>>>Spikes from 5-10 milliseconds
>>>>>
> 
> 
>>>I'm going to try your suggestion of doing a stack dump
>>>when the driver encounters the large spikes in IRQ latency,
>>>to determine if something is leaving interrupts disabled.
>>
>>I wasn't very informative, alas.
> 
> 
> Yeah, I've been reading through the 2.5.69 patch again and
> could not really see anything that related to the
> stack dump.
> 
> 
>>>That will not address the fact that the minimum
>>>latency has jumped from 20usec (2.4.20 - 2.5.68) to 100usec
>>>(2.5.69). This may actually be two separate problems
>>>introduced with 2.5.69
>>
>>Can you pinpoint a kernel version at which it started to happen?
> 
> 
> Exactly with 2.5.69
> 
> 2.5.68 works fine as do earlier versions back to 2.4.20-8
> (earliest tested for this problem). All these versions have
> very consistant latencies as described above.
> 
> The problem definately started with the 2.5.69
> 

Try to narrow it down with the 2.5.68-bk snapshots.

--
				Brian Gerst