On 2015-04-24 08:54, Mike Galbraith wrote: > On Thu, 2015-04-23 at 17:00 -0400, Steven Rostedt wrote: >> On Thu, 23 Apr 2015 09:19:26 +0200 >> Mike Galbraith <umgwanakikbuti@xxxxxxxxx> wrote: >> >>>> CC kernel/irq_work.o >>>> In file included from ../include/asm-generic/percpu.h:6:0, >>>> from ../arch/x86/include/asm/percpu.h:522, >>>> from ../arch/x86/include/asm/current.h:5, >>>> from ../arch/x86/include/asm/processor.h:15, >>>> from ../arch/x86/include/asm/irq_work.h:4, >>>> from ../include/linux/irq_work.h:47, >>>> from ../kernel/irq_work.c:11: >>>> ../kernel/irq_work.c: In function ‘irq_work_queue_on’: >>>> ../kernel/irq_work.c:85:17: error: ‘hirq_work_list’ undeclared >>>> (first use in this function) >>>> &per_cpu(hirq_work_list, cpu)); >>> >>> Aw poo, so that's just what I _thought_ it was for. >> >> It helps optimization but does nothing for undefined symbols. >> >> That said, why don't we clean up that irq_work code and at least >> declare both lists, and get rid of all the #ifdefs. I wonder if gcc is >> smart enough to not allocate a static variable if it happens to be >> optimized out? > > Nope, it didn't notice a thing. > > This is a stab at that cleanup. Usable as is with Jan's ok, or as > fodder for your bitmaster-9000 patch shredder, or whatever. Box works > and it makes line count shrink... > > I downgraded evolution v3.16->v3.12 to restore its ability to read it's > own fscking "Preformatted" switch, so whitespace should be fine. > > Oh, btw, if anyone (else) makes a 4.1-rt, your rt push work will want > one of those nifty hirq tags lest box make boom due to trying to do that > not only way late, but with irqs enabled which pisses sched all off. > > Subject: [PATCH RT 3.18] irq_work: Provide a soft-irq based queue > Date: Thu, 16 Apr 2015 18:28:16 +0200 > From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx> > > Instead of turning all irq_work requests into lazy ones on -rt, just > move their execution from hard into soft-irq context. > > This resolves deadlocks of ftrace which will queue work from arbitrary > contexts, including those that have locks held that are needed for > raising a soft-irq. > > Mike: cleanup ifdef mess and kill hirq_work_list. We need two lists, > and already have them, merely need to select according to work type. > In -rt all work not tagged for hirq execution is queued to the lazy > list and runs via irq_work_tick(). Raising SOFTIRQ_TIMER is always > done via IPI for deadlock safety, if the work item is not a lazy work > or the tick is stopped, fire IPI immediately, otherwise let it wait. > IOW, lazy work is lazy in -rt only until someone queues immediate work. The approach looks good to me, but the commit log deserves a rework now. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
