Module Name: src Committed By: ad Date: Fri Nov 22 23:36:25 UTC 2019
Modified Files: src/sys/arch/amd64/amd64: locore.S src/sys/arch/x86/x86: cpu.c Log Message: - On-demand zeroing pages with MOVNTI is crazy. It empties L1/L2/L3. - Disable zeroing in the idle loop. That needs a cache-friendly strategy. Result: 3 to 4% reduction in kernel build time on my test system. Inspired by a discussion with Mateusz Guzik and David Maxwell. To generate a diff of this commit: cvs rdiff -u -r1.191 -r1.192 src/sys/arch/amd64/amd64/locore.S cvs rdiff -u -r1.174 -r1.175 src/sys/arch/x86/x86/cpu.c Please note that diffs are not public domain; they are subject to the copyright notices on the relevant files.
Modified files: Index: src/sys/arch/amd64/amd64/locore.S diff -u src/sys/arch/amd64/amd64/locore.S:1.191 src/sys/arch/amd64/amd64/locore.S:1.192 --- src/sys/arch/amd64/amd64/locore.S:1.191 Thu Nov 21 19:27:54 2019 +++ src/sys/arch/amd64/amd64/locore.S Fri Nov 22 23:36:25 2019 @@ -1,4 +1,4 @@ -/* $NetBSD: locore.S,v 1.191 2019/11/21 19:27:54 ad Exp $ */ +/* $NetBSD: locore.S,v 1.192 2019/11/22 23:36:25 ad Exp $ */ /* * Copyright-o-rama! @@ -1519,24 +1519,16 @@ END(sse2_idlezero_page) /* * void pagezero(vaddr_t va) * - * Zero a page without polluting the cache. + * Zero a page. */ ENTRY(pagezero) - movq $-PAGE_SIZE,%rdx - subq %rdx,%rdi + pushq %rbp + movq %rsp,%rbp + movq $(PAGE_SIZE / 8),%rcx xorq %rax,%rax -1: - movnti %rax,(%rdi,%rdx) - movnti %rax,8(%rdi,%rdx) - movnti %rax,16(%rdi,%rdx) - movnti %rax,24(%rdi,%rdx) - movnti %rax,32(%rdi,%rdx) - movnti %rax,40(%rdi,%rdx) - movnti %rax,48(%rdi,%rdx) - movnti %rax,56(%rdi,%rdx) - addq $64,%rdx - jne 1b - sfence + rep + stosq + leave ret END(pagezero) Index: src/sys/arch/x86/x86/cpu.c diff -u src/sys/arch/x86/x86/cpu.c:1.174 src/sys/arch/x86/x86/cpu.c:1.175 --- src/sys/arch/x86/x86/cpu.c:1.174 Tue Nov 5 20:19:17 2019 +++ src/sys/arch/x86/x86/cpu.c Fri Nov 22 23:36:25 2019 @@ -1,4 +1,4 @@ -/* $NetBSD: cpu.c,v 1.174 2019/11/05 20:19:17 maxv Exp $ */ +/* $NetBSD: cpu.c,v 1.175 2019/11/22 23:36:25 ad Exp $ */ /* * Copyright (c) 2000-2012 NetBSD Foundation, Inc. @@ -62,7 +62,7 @@ */ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.174 2019/11/05 20:19:17 maxv Exp $"); +__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.175 2019/11/22 23:36:25 ad Exp $"); #include "opt_ddb.h" #include "opt_mpbios.h" /* for MPDEBUG */ @@ -723,7 +723,7 @@ cpu_boot_secondary_processors(void) tsc_tc_init(); /* Enable zeroing of pages in the idle loop if we have SSE2. */ - vm_page_zero_enable = ((cpu_feature[0] & CPUID_SSE2) != 0); + vm_page_zero_enable = false; /* ((cpu_feature[0] & CPUID_SSE2) != 0); */ } #endif