Messages in this thread | | | Subject | Re: [PATCH 1/3] printk: Release console_sem after logbuf_lock | From | Peter Zijlstra <> | Date | Fri, 10 Jun 2011 14:42:44 +0200 |
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On Fri, 2011-06-10 at 14:41 +0200, Peter Zijlstra wrote: > On Fri, 2011-06-10 at 14:34 +0200, Ingo Molnar wrote: > > * Peter Zijlstra <peterz@infradead.org> wrote: > > > > > thinking that that would have my printk stmts appear on both the > > > fbcon as well as the serial line. But they fail to appear on the > > > latency tracer (current max was 165us waking an idle cpu). > > > > Have you removed this bit: > > > > spin_unlock(&logbuf_lock); > > stop_critical_timings(); /* don't trace print latency */ > > call_console_drivers(_con_start, _log_end); > > start_critical_timings(); > > local_irq_restore(flags); > > > > which hides the latencies from the latency tracer? > > it shouldn't those flags come from spin_lock_irqsave(), which already > has IRQs disabled, so the restore shouldn't re-enable them. > > Hmm,. that might actually already be true for mainline too, yeah, looks > like we call vprintk()->console_unlock() with IRQs-disabled. > > Hohumm..
Also, I used the preemptirqoff tracer, so even if it did re-enable interrupts we should still have preemption disabled and still catch the latency.
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