From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jozef Martiniak -X (jozmarti - PANTHEON TECHNOLOGIES at Cisco)"
 <jozmarti@cisco.com>
Subject: Re: [PATCH] rte_delay_us can be replaced with user
 function
Date: Tue, 19 Jul 2016 13:52:38 +0000
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 <81613915.CvR5looQMP@xps13>
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To: Thomas Monjalon <thomas.monjalon@6wind.com>
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Hi,

On Tue, 2016-07-19 at 15:21 +0200, Thomas Monjalon wrote:
Hi,
>=20
> 2016-07-19 14:42, jozmarti@cisco.com:
> > when running single-core, some drivers tend to call rte_delay_us for a
> > long time, and that is causing packet drops.
> > Attached patch introduces 2 new functions:
> >=20
> > void rte_delay_us_callback_register(void(*userfunc)(unsigned));
> > void rte_delay_us_callback_unregister(void);
> >=20
> > First one replaces rte_delay_us with userfunc and second one restores
> > original rte_delay_us.
>=20
> I think we could avoid the function unregister by exporting the
> default implementation (let's say rte_delay_us_block).
>=20

I think register/unregister is the standard way how to handle callbacks. Un=
register func is now "empty" but can be extended in the future.

> > +REGISTER_TEST_COMMAND(user_delay_us, test_user_delay_us);
>=20
> Thanks for providing an unit test.
>=20
>=20
> > --- a/lib/librte_eal/common/eal_common_timer.c
> > +++ b/lib/librte_eal/common/eal_common_timer.c
> >  void
> >  rte_delay_us(unsigned us)
> >  {
> > +	if (unlikely(rte_delay_us_override !=3D NULL))
> > +	{
> > +	    rte_delay_us_override(us);
> > +	    return;
> > +	}
>=20
> Why not always call the registered callback and initialize it
> to the default implementation (maybe using a constructor)?
>=20
I wanted to touch as few things as possible with this patch.