Date: Fri, 2 Sep 2016 19:32:56 -0700 From: Adrian Chadd <adrian.chadd@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: FreeBSD-arch Arch <freebsd-arch@freebsd.org> Subject: Re: pause_ms() wrapper Message-ID: <CAJ-Vmonn78oPqCrfsKsuRqzgcX6Fz%2B1n=Pp1RxLg0yZcmtqZvQ@mail.gmail.com> In-Reply-To: <2960854.iLOY0Gxipb@ralph.baldwin.cx> References: <2960854.iLOY0Gxipb@ralph.baldwin.cx>
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Can we please name it something that indicates it's not designed to be exact?
The .. exactness of various calls has been a thorn in the side of a
few people, myself included. I've been bitten by the callout precision
changes :(
I like linux's usleep_range() for example. It makes it obvious that
you can get anything inside that bar. How hard is that to do with
pause_sbt() ?
-adrian
On 2 September 2016 at 12:22, John Baldwin <jhb@freebsd.org> wrote:
> Figuring out the 3 arguments required for pause_sbt() can be a bit
> non-obvious (at least to me). To that end, I'd like to have a simple
> wrapper around pause_sbt() that accepts milliseconds. It would align
> itself on hardclock similar to the hz-based wrapper. OTOH, we could
> change the implementation at some point to use something more resaonable
> in terms of precision, etc. However, most of the time when I want to
> sleep for N milliseconds (or N microseconds) due to some hardware spec,
> I don't really have a strong opinion on the precision. Having all the
> callers try to figure out a precision would seem to inevitably result
> in inconsistencies. To start with I'd like to just add this:
>
> #define pause_ms(wmesg, msecs) \
> pause_sbt((wmesg), SBT_1MS * (msecs), 0, C_HARDCLOCK)
>
> Which you can use as 'pause_ms("pcieflr", 100);'.
>
> Are there any objections? Do people want other wrappers? Should we
> use more nuanced math similar to what was done in r296775?
>
> --
> John Baldwin
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