[src/trunk]: src/sys/arch/x86/x86 Don't do extra work finding the power of 2 ...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c9e78fbc2b9b
branches:  trunk
changeset: 955721:c9e78fbc2b9b
user:      christos <christos%NetBSD.org@localhost>
date:      Fri Oct 09 21:14:05 2020 +0000

description:
Don't do extra work finding the power of 2 for values we are not going to
use. Explain that cpu_hatch has not been called yet, so no cpu_probe either
so the cache info is 0 for AP's.

diffstat:

 sys/arch/x86/x86/cpu.c |  53 +++++++++++++++++++++++++++++--------------------
 1 files changed, 31 insertions(+), 22 deletions(-)

diffs (84 lines):

diff -r 75e75b0513c5 -r c9e78fbc2b9b sys/arch/x86/x86/cpu.c
--- a/sys/arch/x86/x86/cpu.c    Fri Oct 09 19:41:02 2020 +0000
+++ b/sys/arch/x86/x86/cpu.c    Fri Oct 09 21:14:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cpu.c,v 1.198 2020/08/09 15:32:44 christos Exp $       */
+/*     $NetBSD: cpu.c,v 1.199 2020/10/09 21:14:05 christos Exp $       */
 
 /*
  * Copyright (c) 2000-2020 NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.198 2020/08/09 15:32:44 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.199 2020/10/09 21:14:05 christos Exp $");
 
 #include "opt_ddb.h"
 #include "opt_mpbios.h"                /* for MPDEBUG */
@@ -274,11 +274,17 @@
 static void
 cpu_vm_init(struct cpu_info *ci)
 {
-       int ncolors = 2, i;
+       unsigned int ncolors = 2;
 
-       for (i = CAI_ICACHE; i <= CAI_L2CACHE; i++) {
+       /*
+        * XXX: for AP's the cache info has not been initialized yet
+        * but that does not matter because uvm only pays attention at
+        * the maximum only. We should fix it once cpus have different
+        * cache sizes.
+        */
+       for (unsigned int i = CAI_ICACHE; i <= CAI_L2CACHE; i++) {
                struct x86_cache_info *cai;
-               int tcolors;
+               unsigned int tcolors;
 
                cai = &ci->ci_cinfo[i];
 
@@ -293,24 +299,27 @@
                default:
                        tcolors /= cai->cai_associativity;
                }
-               ncolors = uimax(ncolors, tcolors);
-               /*
-                * If the desired number of colors is not a power of
-                * two, it won't be good.  Find the greatest power of
-                * two which is an even divisor of the number of colors,
-                * to preserve even coloring of pages.
-                */
-               if (ncolors & (ncolors - 1) ) {
-                       int try, picked = 1;
-                       for (try = 1; try < ncolors; try *= 2) {
-                               if (ncolors % try == 0) picked = try;
-                       }
-                       if (picked == 1) {
-                               panic("desired number of cache colors %d is "
-                               " > 1, but not even!", ncolors);
-                       }
-                       ncolors = picked;
+               if (tcolors <= ncolors)
+                       continue;
+               ncolors = tcolors;
+       }
+
+       /*
+        * If the desired number of colors is not a power of
+        * two, it won't be good.  Find the greatest power of
+        * two which is an even divisor of the number of colors,
+        * to preserve even coloring of pages.
+        */
+       if (ncolors & (ncolors - 1) ) {
+               unsigned int try, picked = 1;
+               for (try = 1; try < ncolors; try *= 2) {
+                       if (ncolors % try == 0) picked = try;
                }
+               if (picked == 1) {
+                       panic("desired number of cache colors %u is "
+                       " > 1, but not even!", ncolors);
+               }
+               ncolors = picked;
        }
 
        /*