Messages in this thread Patch in this message | | | Date | Thu, 6 Jul 2006 15:31:47 -0500 (CDT) | From | "Mark Langsdorf" <> | Subject | [PATCH] Allow all Opteron processors to change pstate at same time |
| |
The current generation of Opteron processors do not provide a frequency independent TSC. This causes wild gettimeofday skew on systems that enable cpufreq while using TSC as a gtod source.
This patch provides a workaround by changing all processors to the same frequency at the same time, so that the TSC on each processor never increments at a different rate than the TSC on another processor.
the "powernow-k8.tscsync=1" options enables simeltameous transitions. Other options are necessary to force the use of TSC as a gtod source.
This patch should apply cleanly to the 2.6.18-rc1 kernel.
-Mark Langsdorf AMD, Inc.
signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com> --- linux-mm2-2.6.17-rc6/arch/i386/kernel/cpu/cpufreq/powernow-k8.c.old 2006-06-12 12:22:06.000000000 -0500 +++ linux-mm2-2.6.17-rc6/arch/i386/kernel/cpu/cpufreq/powernow-k8.c 2006-06-13 15:43:39.000000000 -0500 @@ -46,13 +46,15 @@ #define PFX "powernow-k8: " #define BFX PFX "BIOS error: " -#define VERSION "version 2.00.00" +#define VERSION "version 2.10.00" #include "powernow-k8.h" /* serialize freq changes */ static DEFINE_MUTEX(fidvid_mutex); static struct powernow_k8_data *powernow_data[NR_CPUS]; +static int *req_state = NULL; +static int tscsync __initdata = 0; static int cpu_family = CPU_OPTERON; @@ -205,6 +207,17 @@ static int write_new_fid(struct powernow dprintk("writing fid 0x%x, lo 0x%x, hi 0x%x\n", fid, lo, data->plllock * PLL_LOCK_CONVERSION); + if (tscsync) { + int i; + cpumask_t oldmask = current->cpus_allowed; + for_each_online_cpu(i) { + set_cpus_allowed(current, cpumask_of_cpu(i)); + schedule(); + wrmsr(MSR_FIDVID_CTL, lo & ~MSR_C_LO_INIT_FID_VID, data->plllock * PLL_LOCK_CONVERSION); + } + set_cpus_allowed(current, oldmask); + schedule(); + } do { wrmsr(MSR_FIDVID_CTL, lo, data->plllock * PLL_LOCK_CONVERSION); if (i++ > 100) { @@ -247,6 +260,17 @@ static int write_new_vid(struct powernow dprintk("writing vid 0x%x, lo 0x%x, hi 0x%x\n", vid, lo, STOP_GRANT_5NS); + if (tscsync) { + int i; + cpumask_t oldmask = current->cpus_allowed; + for_each_online_cpu(i) { + set_cpus_allowed(current, cpumask_of_cpu(i)); + schedule(); + wrmsr(MSR_FIDVID_CTL, lo & ~MSR_C_LO_INIT_FID_VID, STOP_GRANT_5NS); + } + set_cpus_allowed(current, oldmask); + schedule(); + } do { wrmsr(MSR_FIDVID_CTL, lo, STOP_GRANT_5NS); if (i++ > 100) { @@ -386,7 +410,8 @@ static int core_frequency_transition(str } if (data->currfid == reqfid) { - printk(KERN_ERR PFX "ph2 null fid transition 0x%x\n", data->currfid); + if (!tscsync) + printk(KERN_ERR PFX "ph2 null fid transition 0x%x\n", data->currfid); return 0; } @@ -960,9 +985,21 @@ static int transition_frequency_fidvid(s u32 vid = 0; int res, i; struct cpufreq_freqs freqs; + cpumask_t changing_cores; dprintk("cpu %d transition to index %u\n", smp_processor_id(), index); + /* if all processors are transitioning in step, find the highest + * current state and go to that + */ + + if (tscsync && req_state) { + req_state[smp_processor_id()] = index; + for_each_online_cpu(i) + if (req_state[i] < index) + index = req_state[i]; + } + /* fid/vid correctness check for k8 */ /* fid are the lower 8 bits of the index we stored into * the cpufreq frequency table in find_psb_table, vid @@ -983,6 +1020,8 @@ static int transition_frequency_fidvid(s } if ((fid < HI_FID_TABLE_BOTTOM) && (data->currfid < HI_FID_TABLE_BOTTOM)) { + if (tscsync && (data->currfid == fid)) + return 0; printk(KERN_ERR PFX "ignoring illegal change in lo freq table-%x to 0x%x\n", data->currfid, fid); @@ -994,7 +1033,11 @@ static int transition_frequency_fidvid(s freqs.old = find_khz_freq_from_fid(data->currfid); freqs.new = find_khz_freq_from_fid(fid); - for_each_cpu_mask(i, *(data->available_cores)) { + if (tscsync) + changing_cores = cpu_online_map; + else + changing_cores = *(data->available_cores); + for_each_cpu_mask(i, changing_cores) { freqs.cpu = i; cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); } @@ -1002,10 +1045,16 @@ static int transition_frequency_fidvid(s res = transition_fid_vid(data, fid, vid); freqs.new = find_khz_freq_from_fid(data->currfid); - for_each_cpu_mask(i, *(data->available_cores)) { + for_each_cpu_mask(i, changing_cores) { freqs.cpu = i; cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); } + if (tscsync) + for_each_online_cpu(i) + if (powernow_data[i]) { + powernow_data[i]->currfid = data->currfid; + powernow_data[i]->currvid = data->currvid; + } return res; } @@ -1054,7 +1103,7 @@ static int powernowk8_target(struct cpuf u32 checkfid; u32 checkvid; unsigned int newstate; - int ret = -EIO; + int ret = 0;//-EIO; if (!data) return -EINVAL; @@ -1089,7 +1138,7 @@ static int powernowk8_target(struct cpuf dprintk("targ: curr fid 0x%x, vid 0x%x\n", data->currfid, data->currvid); - if ((checkvid != data->currvid) || (checkfid != data->currfid)) { + if (!tscsync && ((checkvid != data->currvid) || (checkfid != data->currfid))) { printk(KERN_INFO PFX "error - out of sync, fix 0x%x 0x%x, vid 0x%x 0x%x\n", checkfid, data->currfid, checkvid, data->currvid); @@ -1100,7 +1149,6 @@ static int powernowk8_target(struct cpuf goto err_out; mutex_lock(&fidvid_mutex); - powernow_k8_acpi_pst_values(data, newstate); if (cpu_family) @@ -1137,6 +1185,32 @@ static int powernowk8_verify(struct cpuf return cpufreq_frequency_table_verify(pol, data->powernow_table); } +/* On an MP system that is transitioning all cores in sync, adjust the + * vids for each frequency to the highest. Otherwise, systems made up + * of different steppings may fail. + */ +static void sync_tables(int curcpu) +{ + int j; + for (j = 0; j < powernow_data[curcpu]->numps; j++) { + int i; + int maxvid = 0; + for_each_online_cpu(i) { + int testvid; + if (!powernow_data[i] || !powernow_data[i]->powernow_table) + continue; + testvid = powernow_data[i]->powernow_table[j].index & 0xff00; + if (testvid > maxvid) + maxvid = testvid; + } + for_each_online_cpu(i) { + if (!powernow_data[i] || ! powernow_data[i]->powernow_table) + continue; + powernow_data[i]->powernow_table[j].index &= 0xff; + powernow_data[i]->powernow_table[j].index |= maxvid; + } + } +} /* per CPU init entry point to the driver */ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol) { @@ -1200,6 +1274,9 @@ static int __cpuinit powernowk8_cpu_init if (!cpu_family) fidvid_msr_init(); + if (tscsync && (cpu_family == CPU_OPTERON)) + req_state[pol->cpu] = 0; + /* run on any CPU again */ set_cpus_allowed(current, oldmask); @@ -1241,6 +1318,8 @@ static int __cpuinit powernowk8_cpu_init powernow_data[pol->cpu] = data; + if (tscsync && (cpu_family == CPU_OPTERON)) + sync_tables(pol->cpu); return 0; err_out: @@ -1323,6 +1402,13 @@ static int __cpuinit powernowk8_init(voi } if (supported_cpus == num_online_cpus()) { + if (tscsync) { + req_state = kzalloc(sizeof(int)*NR_CPUS, GFP_KERNEL); + if (!req_state) { + printk(KERN_ERR PFX "Unable to allocate memory!\n"); + return -ENOMEM; + } + } printk(KERN_INFO PFX "Found %d %s " "processors (" VERSION ")\n", supported_cpus, boot_cpu_data.x86_model_id); @@ -1337,6 +1423,9 @@ static void __exit powernowk8_exit(void) { dprintk("exit\n"); + if (tscsync) + kfree(req_state); + cpufreq_unregister_driver(&cpufreq_amd64_driver); } @@ -1346,3 +1435,6 @@ MODULE_LICENSE("GPL"); late_initcall(powernowk8_init); module_exit(powernowk8_exit); + +module_param(tscsync, int, 0); +MODULE_PARM_DESC(tscsync, "enable tsc by synchronizing powernow-k8 changes"); | |