Date: Mon, 20 Apr 2009 17:32:06 +0200 From: Marius Strobl <marius@alchemy.franken.de> To: Robert Watson <rwatson@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, John Baldwin <jhb@freebsd.org> Subject: Re: svn commit: r191291 - in head: lib/libthr/thread libexec/rtld-elf/amd64 libexec/rtld-elf/arm libexec/rtld-elf/i386 libexec/rtld-elf/ia64 libexec/rtld-elf/mips libexec/rtld-elf/powerpc libexec/rtld-... Message-ID: <20090420153205.GB59939@alchemy.franken.de> In-Reply-To: <alpine.BSF.2.00.0904201352230.71062@fledge.watson.org> References: <200904192302.n3JN2o6Z023217@svn.freebsd.org> <200904200822.17158.jhb@freebsd.org> <alpine.BSF.2.00.0904201352230.71062@fledge.watson.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, Apr 20, 2009 at 02:00:56PM +0100, Robert Watson wrote: > > On Mon, 20 Apr 2009, John Baldwin wrote: > > >> Now that the kernel defines CACHE_LINE_SIZE in machine/param.h, use > >> that definition in the custom locking code for the run-time linker > >> rather than local definitions. > > > >Perhaps CACHE_LINE_SIZE for ia64 and sparc64 should be 128 since that is > >what rtld used? > > I'm happy with whatever size the platform maintainers would like. I've > changed ia64, sparc64, and sun4v kernel CACHE_LINE_SIZE definitions to 128, > and powerpc was already 128, but left the others at 64 bytes until such > time as we have some useful numbers or informat ionto suggest another > choice would be better. All I'm really looking for here is a baseline > constant to use, I have no particular vested interest in specific values > for the constants. > For sparc64 the cache line size should be ideally determined at runtime using Open Firmware, however I'm not aware of a sun4u CPU having a L1 data- or instruction cache line size greater than 32 bytes though. Some of them have a prefetch cache with a line size of 64 bytes though which besides for the prefetch instructions is used autonomously by the CPU when fetching from the L2 cache (which can have a line size of up to 512 bytes AFAICT). I'm not aware how relevant this is for the intended use of CACHE_LINE_SIZE, but a value of of 64 seems appropriate for sparc64 in order also cover the prefetch cache. Marius
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20090420153205.GB59939>