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    SubjectRe: [PATCH 1/3] printk: Release console_sem after logbuf_lock
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    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..


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