Re: RCU (or equivalent) for NetBSD?

[Dennis Ferguson <dennis.c.ferguson%gmail.com@localhost>]

On 3 Mar, 2013, at 19:26 , "J. Hannken-Illjes" 
<hannken%eis.cs.tu-bs.de@localhost> wrote:
>> The basic functions seem to be a perfect fit.
>> 
>> The only bit I'm confused about is what the implication of
>> 
>>   The read operations may happen from software interrupt at the
>>   IPL_SOFTCLOCK symbolic level.
>> 
>> is for an application that wants to use this interface.  Processing of 
>> packets
>> arriving from hardware interfaces is traditionally run at IPL_SOFTNET, is the
>> above telling me a reader can't use pserialize(9) if it is running at that
>> level?
> 
> The opposite: pserialize may be used from soft interrupt context.

I assume it can also be used in process context, that is in code running as
a result of a system call (which is the context the other half of packets
processed through the network stack on a host are handled in).

If it is the case that pserialize can be used from soft interrupt context
at any priority level, however, then why does the man page call out 
IPL_SOFTCLOCK
in particular?  IPL_SOFTNET is usually a higher priority and in theory can 
interrupt
IPL_SOFTCLOCK processing; is that really okay?

Dennis Ferguson