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    SubjectRe: [PATCH] printk: Add printk_flush() to force buffered text to console
    On Sat, Jun 16, 2012 at 08:59:03AM +0200, Ingo Molnar wrote:
    >
    > * Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
    >
    > > On Fri, Jun 15, 2012 at 02:04:30PM +0200, Ingo Molnar wrote:
    > > >
    > > > * Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
    > > >
    > > > > On Fri, Jun 15, 2012 at 12:22:33PM +0800, Fengguang Wu wrote:
    > > > > > > I actually would like to make these more compact. As all my test box
    > > > > > > consoles go through serial ports, just booting through this takes more
    > > > > > > time the the compile itself.
    > > > > >
    > > > > > The tests took 23 seconds boot time on one kernel:
    > > > > >
    > > > > > [ 0.152934] Testing tracer nop: PASSED
    > > > > > ...1577 lines total...
    > > > > > [ 23.206550] Testing kprobe tracing: OK
    > > > > >
    > > > > > And 135 seconds in another bloated kernel:
    > > > > >
    > > > > > [ 115.396441] Testing event 9p_client_req: OK
    > > > > > ...2545 lines total...
    > > > > > [ 240.268783] Testing kprobe tracing: OK
    > > > > >
    > > > > > I'd appreciate if the boot time can be reduced. Because I'm doing
    > > > > > kernel boot tests for *every single* commits.
    > > > > >
    > > > > > It may look insane amount of work, but it's still manageable: with 10
    > > > > > kvm instances each take 1 minute to boot test a kernel, I can boot
    > > > > > test 60*24*10=14400 kernels in one day. That's a rather big number.
    > > > > > That allows me to run more cpu/vm/io stress tests for each kernel :-)
    > > > >
    > > > > Do you really want to enable those tests for your test
    > > > > kernels? Can they fail if we mess up other parts of the
    > > > > kernel, or do they only test the tracing portions?
    > > >
    > > > These printk's are useful, are used for a specific (albeit
    > > > limited) purpose and were and continue to be useful in that
    > > > role.
    > > >
    > > > The changes Steve bisected to broke this use of printk().
    > >
    > > And note, fixed others :)
    >
    > Sorry, the "we fix some bugs and introduce others" stance is not
    > a valid response to a regression. Either fix *all* regressions
    > or revert the original change. Simple and robust policy, isn't
    > it?

    You are right, to a point :)

    > > > Please apply Steve's fix, fix it yourself or revert the
    > > > changes that regressed printk().
    > >
    > > I thought Steve's patch was just a RFC thing, is it really
    > > something that everyone wants to see applied?
    >
    > You mean the adding of an API to flush buffered output when
    > that's the desired outcome? Why the heck should we *not* want
    > that? Either I'm the weird one or you are being difficult ;-)

    Sorry, no, I was referring to the fact that he said he didn't really
    like it because of the timestamp garbage in the line.

    thanks,

    greg k-h


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