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    SubjectRe: [PATCH 2/2] selftests/x86/fsgsbase: Default to trying to run the test repeatedly

    * Mark Brown <broonie@kernel.org> wrote:

    > On Mon, Feb 11, 2019 at 09:49:16AM +0100, Ingo Molnar wrote:
    >
    > > So this isn't very user-friendly either, previously it would run a
    > > testcase and immediately provide output.
    >
    > > Now it's just starting and 'hanging':
    >
    > > galatea:~/linux/linux/tools/testing/selftests/x86> ./fsgsbase_64
    >
    > > I got bored and Ctrl-C-ed it after ~30 seconds.
    >
    > > How long is this supposed to run, and why isn't the user informed?
    >
    > On Intel systems I've got access to it's tended to only run for less
    > than 10 seconds for me with excursions up to ~30s at most, I'd have
    > projected it to be about a minute if the tests pass. However retesting
    > with Debian's v4.19 kernel it seems to be running a lot more stably so
    > we're now seeing it run to completion reliably when just one copy of the
    > test is running.
    >
    > AFAICT it's not terribly idiomatic to provide much output, and anything
    > that was per iteration would be *way* too spammy.

    Certainly - but a "please wait" and updating the current count via \r
    once every second isn't spammy.

    > > Also, testcases should really be short, so I think a better approach
    > > would be to thread the test-case and start an instance on every CPU. That
    > > should also excercise SMP bugs, if any.
    >
    > Well, a *better* approach would be for the underlying issue that the
    > test is finding to be fixed.
    >
    > I didn't look at adding more threads as the test case is already
    > threaded, it does seem that running multiple copies simultaneously makes
    > things reproduce more quickly so it's definitely useful though it's
    > still taking multiple iterations.

    multiple iterations are fine - waiting a minute with zero output on the
    console isn't.

    Thanks,

    Ingo

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