Date: Mon, 20 Apr 2009 14:39:43 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: Bruce Evans <brde@optusnet.com.au> Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r191276 - in head/sys: amd64/include arm/include i386/include ia64/include mips/include powerpc/include sparc64/include sun4v/include Message-ID: <alpine.BSF.2.00.0904201438380.82842@fledge.watson.org> In-Reply-To: <20090420174802.F58065@delplex.bde.org> References: <200904192019.n3JKJDa6019179@svn.freebsd.org> <20090420174802.F58065@delplex.bde.org>
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On Mon, 20 Apr 2009, Bruce Evans wrote: >> +#ifndef CACHE_LINE_SHIFT >> +#define CACHE_LINE_SHIFT 6 >> +#endif >> +#define CACHE_LINE_SIZE (1 << CACHE_LINE_SHIFT) > > This still has the bogus ifdef. Overriding the definition is difficult to > do consistently even in a kernel with no modules, since CACHE_LINE_SIZE is > not a kernel option. Overriding the definition makes negative sense since > the value is a maximum-maximum (possibly larger than strictly needed) so > that it can be constant. OK, I've made this change. My hope is that most applications don't resort to including sys/param.h and using CACHE_LINE_SIZE -- most will be able to query it at run-time using interfaces we don't yet have (such as sysconf(3) and some appropriate constant). I also hope that most kernel consumers will be able to use a run-time tuned version (which we also don't yet have). Robert N M Watson Computer Laboratory University of Cambridge
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