Re: Collapsing RT signals ...

[Davide Libenzi]

On 25-Jun-2001 Dan Kegel wrote:
> Davide Libenzi <[e-mail]> wrote:
>> I'm making some test with RT signals and looking at how they're implemented
>> inside the kernel.
>> After having experienced frequent queue overflow signals I looked at how
>> signals are queued inside the task_struct.
>> There's no signals optimization inside and this make the queue length
>> depending
>> on the request rate instead of the number of connections.
>> It can happen that two ( or more ) POLL_IN signals are queued with a single
>> read() that sweep the buffer leaving other signals to issue reads ( read
>> this
>> as user-mode / kernel-mode switch ) that will fail due lack of data.
>> So for every "superfluous" signal we'll have two user-mode / kernel-mode
>> switches, one for signal delivery and one for a failing read().
>> I'm just thinking at a way to optimize the signal delivery that is ( draft )
>> :
>> ...
> 
> I agree, the queue overflow case is a pain in the butt.
> 
> Before you get too far coding up your idea, have you read
> http://marc.theaimsgroup.com/?l=linux-kernel&m=99023775430848&w=2
> ?  He's already implemented and benchmarked a variation on this
> idea, maybe you could vet his code.  He has taken it a step
> further than perhaps you were going to.

I'll do for sure, thank You.

> 
> (See also http://www.kegel.com/c10k.html#nb.sigio )

I already knew Your document, pretty cool.

- Davide