* Huang Ying <ying.huang@xxxxxxxxx> wrote: > > That's where 'active filters' come into the picture - see my other mail > > (that was in the context of unidentified NMI errors/events) where i > > outlined how they would work in this case and elsewhere. Via active filters > > we could share most of the code, gain access to the events and still have > > kernel driven policy action. > > Is that something as follow? > > - NMI handler run for the hardware error, where hardware error > information is collected and put into perf ring buffer as 'event'. Correct. Note that for MCE errors we want the 'persistent event' framework Boris has posted: we want these events to be buffered up to a point even if there is no tool listening in on them: - this gives us boot-time MCE error coverage - this protects us against a logging daemon being restarted and events getting lost > - Some 'active filters' are run for each 'event' in NMI context. Yeah. Whether it's a human-ASCII space 'filter' or really just a callback you register with that event is secondary - both would work. > - Some operations can not be done in NMI handler, so they are delayed to > an IRQ handler (can be done with something like irq_work). Yes. > - Some other 'active filters' are run for each 'event' in IRQ context. > (For memory error, we can call memory_failure_queue() here). Correct. > Where some 'active filters' are kernel built-in, some 'active filters' can be > customized via kernel command line or by user space. Yes. > If my understanding as above is correct, I think this is a general and > complex solution. It is a little hard for user to understand which 'active > filters' are in effect. He may need some runtime assistant to understand the > code (maybe /sys/events/active_filters, which list all filters in effect > now), because that is hard only by reading the source code. Anyway, this is > a design style choice. I don't think it's complex: the built-in rules are in plain sight (can be in the source code or can even be explicitly registered callbacks), the configuration/tooling installed rules will be as complex as the admin or tool wants them to be. > There are still some issues, I don't know how to solve in above framework. > > - If there are two processes request the same type of hardware error > events. One hardware error event will be copied to two ring buffers (each > for one process), but the 'active filters' should be run only once for each > hardware error event. With persistent events 'active filters' should only be attached to the central persistent event. > - How to deal with ring-buffer overflow? For example, there is full of > corrected memory error in ring-buffer, and now a recoverable memory error > occurs but it can not be put into perf ring buffer because of ring-buffer > overflow, how to deal with the recoverable memory error? The solution is to make it large enough. With *every* queueing solution there will be some sort of queue size limit. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
