On Tue, 27 Jan 2009 17:35:11 +1030 Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: > On Monday 26 January 2009 17:31:30 Andrew Morton wrote: > > On Mon, 26 Jan 2009 17:11:43 +1030 Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: > > > > > On Saturday 24 January 2009 18:45:37 Andrew Morton wrote: > > > > Pity the poor reader who comes along trying to work out why this exists. > > > > (chirp, chirp) > > I disagree. It's simple; we create a workqueue and we use it. There's no > confusion here. Reader's first and most important question is "why does this exist". > > > None of these options are appealing... > > > > Can we try harder please? 10 screenfuls of kernel threads in the ps > > output is just irritating. > > > > How about banning the use of work_on_cpu() from schedule_work() > > handlers and then fixing that driver somehow? > > Again, that's how we got here in the first place. I didn't realize the > twisty path by which the acpi cpufreq code could be called. And there > may well be others. So I want work_on_cpu to be completely generic. But it isn't generic. The patch just moved the deadlock from one queue to another. Making work_on_cu() truly generic is quite hard! > But it's a general comment about fixing a general issue. The currently > known case is not directly relevent; that it can happen and it's restricting > the use of this otherwise-general API is. I think we should switch acpi-cpufreq to smp_call_function(), revert this stuff and ban the calling of work_on_cpu() under locks. > A little confused at all this vitriol, Well let's see. - it was badly changelogged - it was badly commented - it's slow. In many ways, including the unnecessary serialisation of each cross-cpu call in acpi-cpufreq. - it consumes a tremendous amount of resources just to fix some acpi locking snafu - it adds yet another zillion kernel threads - it's still deadlockable - it got sent to Linus while still under active discussion - and it got merged - Oleg is the usual workqueue developer and wasn't even cc'ed. - I am the usual workqueue reviewer/merger (and would prefer to remain thus, please) and I wasn't cc'ed either. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
