Date: Sat, 22 Sep 2012 20:46:13 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: freebsd-hackers <freebsd-hackers@FreeBSD.org> Subject: Re: cpu_spinwait in cngetc Message-ID: <505DF965.2020506@FreeBSD.org> In-Reply-To: <50587635.8070007@FreeBSD.org> References: <50587635.8070007@FreeBSD.org>
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on 18/09/2012 16:25 Andriy Gapon said the following: > > (Why[*]) Would anyone object to a change like this? > > diff --git a/sys/kern/kern_cons.c b/sys/kern/kern_cons.c > index 5346bc3..d17846a 100644 > --- a/sys/kern/kern_cons.c > +++ b/sys/kern/kern_cons.c > @@ -384,7 +384,7 @@ cngetc(void) > if (cn_mute) > return (-1); > while ((c = cncheckc()) == -1) > - ; > + cpu_spinwait(); > if (c == '\r') > c = '\n'; /* console input is always ICRNL */ > return (c); > > [*] :-) > I would to re-ping with this question. Is there any architecture where a cpu_spinwait could cause a surprise? Or is universally safe? The most visible place which this change can affect is ddb prompt. -- Andriy Gapon
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