[erlang-patches] Re: Patch for configurable ERTS_DE_BUSY_LIMIT

Raimo Niskanen <>
Tue Jun 8 10:34:46 CEST 2010

On Tue, Jun 08, 2010 at 03:01:16AM -0500, Scott Lystig Fritchie wrote:
> Rickard Green <> wrote:
> rg> It seems reasonable to add a configuration parameter for this.
> rg> However: [...]
> Assuming I followed instructions correctly, version 2 of this new config
> knob should be available via:
>     git fetch git://github.com/slfritchie/otp.git erts_de_busy_limit

Thank you. Will be included in 'pu', but probably after the release.

> Add flag-based setting for 'erts_de_busy_limit' constant
> A prior patch to change the 'erts_de_busy_limit' constant, based on an
> environment variable, was rejected by the Ericsson OTP team because
> environment variables are no longer used for modifying the VM's
> behavior.
> Families of flags like "+s" are devoted to the scheduler (except for
> "+sss"), but it wasn't obvious to me where a "+"-style flag for
> 'erts_de_busy_limit' should go.  So, this patch creates a new family
> of flags, prefixed with "+z", for miscellaneous VM settings.
> The full flag name is "+zerts_de_busy_limit", which goes against the
> tradition of using "+Qmbl" for adjusting some kind of "mumble mumble"
> value but "mumble mumble" is obviously too long to be useful.  If
> "+zerts_de_busy_limit" is too long, then I'll leave it to the OTP team
> to create a tradition-fitting, impossible-to-remember abbreviation to
> use instead.
> I don't a functional Java compiler with the suitable Java compliance
> level, so compiling & running the test suite isn't an option for me
> yet.  I've made the attempt to write a test, but I haven't executed it
> to know if it works.  erlang:system_info(erts_de_busy_limit) was added
> to make a unit test possible.
> The documentation changes are terse but present.  Given the lack of
> Java above, my doc-building toolchain is broken, so I don't know if
> the formatting is correct, sorry.
> -Scott
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/ Raimo Niskanen, Erlang/OTP, Ericsson AB

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