From: Mike Galbraith Date: Wed, 30 Jan 2008 12:30:04 +0000 (+0100) Subject: x86: fix: s2ram + P4 + tsc = annoyance X-Git-Tag: v2.6.25-rc1~1143^2~869 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4c6b8b4d62fb4cb843c32db71e0a8301039908f3;p=linux-2.6 x86: fix: s2ram + P4 + tsc = annoyance s2ram recently became useful here, except for the kernel's annoying habit of disabling my P4's perfectly good TSC. [ 107.894470] CPU 1 is now offline [ 107.894474] SMP alternatives: switching to UP code [ 107.895832] CPU0 attaching sched-domain: [ 107.895836] domain 0: span 1 [ 107.895838] groups: 1 [ 107.896097] CPU1 is down [ 3.726156] Intel machine check architecture supported. [ 3.726165] Intel machine check reporting enabled on CPU#0. [ 3.726167] CPU0: Intel P4/Xeon Extended MCE MSRs (12) available [ 3.726170] CPU0: Thermal monitoring enabled [ 3.726175] Back to C! [ 3.726708] Force enabled HPET at resume [ 3.726775] Enabling non-boot CPUs ... [ 3.727049] CPU0 attaching NULL sched-domain. [ 3.727165] SMP alternatives: switching to SMP code [ 3.727858] Booting processor 1/1 eip 3000 [ 3.727862] CPU 1 irqstacks, hard=b042f000 soft=b042d000 [ 3.738173] Initializing CPU#1 [ 3.798912] Calibrating delay using timer specific routine.. 5986.12 BogoMIPS (lpj=2993061) [ 3.798920] CPU: After generic identify, caps: bfebfbff 00000000 00000000 00000000 00004400 00000000 00000000 00000000 [ 3.798931] CPU: Trace cache: 12K uops, L1 D cache: 8K [ 3.798934] CPU: L2 cache: 512K [ 3.798936] CPU: Physical Processor ID: 0 [ 3.798938] CPU: After all inits, caps: bfebfbff 00000000 00000000 0000b080 00004400 00000000 00000000 00000000 [ 3.798946] Intel machine check architecture supported. [ 3.798952] Intel machine check reporting enabled on CPU#1. [ 3.798955] CPU1: Intel P4/Xeon Extended MCE MSRs (12) available [ 3.798959] CPU1: Thermal monitoring enabled [ 3.799161] CPU1: Intel(R) Pentium(R) 4 CPU 3.00GHz stepping 09 [ 3.799187] checking TSC synchronization [CPU#0 -> CPU#1]: [ 3.819181] Measured 63588552840 cycles TSC warp between CPUs, turning off TSC clock. [ 3.819184] Marking TSC unstable due to: check_tsc_sync_source failed. If check_tsc_warp() is called after initial boot, and the TSC has in the meantime been set (BIOS, user, silicon, elves) to a value lower than the last stored/stale value, we blame the TSC. Reset to pristine condition after every test. Signed-off-by: Mike Galbraith Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c index 9125efe66a..05d8f25de6 100644 --- a/arch/x86/kernel/tsc_sync.c +++ b/arch/x86/kernel/tsc_sync.c @@ -129,23 +129,23 @@ void __cpuinit check_tsc_sync_source(int cpu) while (atomic_read(&stop_count) != cpus-1) cpu_relax(); - /* - * Reset it - just in case we boot another CPU later: - */ - atomic_set(&start_count, 0); - if (nr_warps) { printk("\n"); printk(KERN_WARNING "Measured %Ld cycles TSC warp between CPUs," " turning off TSC clock.\n", max_warp); mark_tsc_unstable("check_tsc_sync_source failed"); - nr_warps = 0; - max_warp = 0; - last_tsc = 0; } else { printk(" passed.\n"); } + /* + * Reset it - just in case we boot another CPU later: + */ + atomic_set(&start_count, 0); + nr_warps = 0; + max_warp = 0; + last_tsc = 0; + /* * Let the target continue with the bootup: */