Date: Thu, 23 Aug 2012 16:55:05 +0100 From: Attilio Rao <attilio@freebsd.org> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: current@freebsd.org Subject: Re: TUNABLE_INT vs TUNABLE_INT_FETCH Message-ID: <CAJ-FndB1PQ%2B8rQLS%2B_Ac-i=xOckTv%2B7aV4Ma9KzJuhUe-DT8Pg@mail.gmail.com> In-Reply-To: <20120823160543.GD3391@onelab2.iet.unipi.it> References: <20120823145420.GB3103@onelab2.iet.unipi.it> <CAJ-FndCSfXvEmYjuEi985JPoiZYStOaqdeYsjyepHS8C55Szkw@mail.gmail.com> <20120823160543.GD3391@onelab2.iet.unipi.it>
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On Thu, Aug 23, 2012 at 5:05 PM, Luigi Rizzo <rizzo@iet.unipi.it> wrote: > On Thu, Aug 23, 2012 at 03:52:56PM +0100, Attilio Rao wrote: >> On 8/23/12, Luigi Rizzo <rizzo@iet.unipi.it> wrote: >> > Hi, >> > I am a bit unclear on what are the pros and cons of using >> > TUNABLE_INT vs TUNABLE_INT_FETCH within a device driver. >> >> TUNABLE_INT is basically the "statically initializer" version of >> TUNABLE_INT_FETCH. >> In short terms, you will use TUNABLE_INT_FETCH() in normal functions, >> while TUNABLE_INT() in data declaration. > > The thing is, do we need the data declaration at all ? What do you mean with "data declaration"? We need to mimic a "static initialization" usage, so what we do is to use the first SYSINIT() family available (SI_SUB_TUNABLES). You also need the env to look for and the static variable to initialize, so for SYSINIT's sake you need to pack them up in a single argument. Attilio -- Peace can only be achieved by understanding - A. Einstein
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