Author: cem Date: Mon Aug 28 22:28:41 2017 New Revision: 322989 URL: https://svnweb.freebsd.org/changeset/base/322989
Log: Drop CACHE_LINE_SIZE to 64 bytes on x86 The actual cache line size has always been 64 bytes. The 128 number arose as an optimization for Core 2 era Intel processors. By default (configurable in BIOS), these CPUs would prefetch adjacent cache lines unintelligently. Newer CPUs prefetch more intelligently. The latest Core 2 era CPU was introduced in September 2008 (Xeon 7400 series, "Dunnington"). If you are still using one of these CPUs, especially in a multi-socket configuration, consider locating the "adjacent cache line prefetch" option in BIOS and disabling it. Reported by: mjg Reviewed by: np Discussed with: jhb Sponsored by: Dell EMC Isilon Modified: head/sys/amd64/include/param.h head/sys/i386/include/param.h head/sys/sys/param.h Modified: head/sys/amd64/include/param.h ============================================================================== --- head/sys/amd64/include/param.h Mon Aug 28 22:14:16 2017 (r322988) +++ head/sys/amd64/include/param.h Mon Aug 28 22:28:41 2017 (r322989) @@ -89,7 +89,7 @@ * CACHE_LINE_SIZE is the compile-time maximum cache line size for an * architecture. It should be used with appropriate caution. */ -#define CACHE_LINE_SHIFT 7 +#define CACHE_LINE_SHIFT 6 #define CACHE_LINE_SIZE (1 << CACHE_LINE_SHIFT) /* Size of the level 1 page table units */ Modified: head/sys/i386/include/param.h ============================================================================== --- head/sys/i386/include/param.h Mon Aug 28 22:14:16 2017 (r322988) +++ head/sys/i386/include/param.h Mon Aug 28 22:28:41 2017 (r322989) @@ -82,7 +82,7 @@ * CACHE_LINE_SIZE is the compile-time maximum cache line size for an * architecture. It should be used with appropriate caution. */ -#define CACHE_LINE_SHIFT 7 +#define CACHE_LINE_SHIFT 6 #define CACHE_LINE_SIZE (1 << CACHE_LINE_SHIFT) #define PAGE_SHIFT 12 /* LOG2(PAGE_SIZE) */ Modified: head/sys/sys/param.h ============================================================================== --- head/sys/sys/param.h Mon Aug 28 22:14:16 2017 (r322988) +++ head/sys/sys/param.h Mon Aug 28 22:28:41 2017 (r322989) @@ -58,7 +58,7 @@ * in the range 5 to 9. */ #undef __FreeBSD_version -#define __FreeBSD_version 1200042 /* Master, propagated to newvers */ +#define __FreeBSD_version 1200043 /* Master, propagated to newvers */ /* * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD, _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
