Re: [PATCH] x86, mce: rework output of MCE banks ownership information

[Mike Travis <travis@sgi.com>]

Hi Ingo,

When running the latest kernel, I still find these in the output:


[    0.722553] Booting Node   0, Processors  #1
[    0.811625] CPU 1 MCA banks SHD:0 SHD:1 CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:7 SHD:8 SHD:9 SHD:12 SHD:13 SHD:14 SHD:15 SHD:16 SHD:17 SHD:18 SHD:19 SHD:20 SHD:21
[    0.812071]  #2
[    0.907468] CPU 2 MCA banks SHD:0 SHD:1 CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:7 SHD:8 SHD:9 SHD:12 SHD:13 SHD:14 SHD:15 SHD:16 SHD:17 SHD:18 SHD:19 SHD:20 SHD:21
[    0.907918]  #3
[    1.003311] CPU 3 MCA banks SHD:0 SHD:1 CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:7 SHD:8 SHD:9 SHD:12 SHD:13 SHD:14 SHD:15 SHD:16 SHD:17 SHD:18 SHD:19 SHD:20 SHD:21
[    1.003750]  #4

Was there anything else needed for this patch to be accepted? 
If it's not acceptable, would simply printing the above as DEBUG
messages be acceptable?  (I'm aware you don't like printing
summaries during init.)

Thanks,
Mike

Mike Travis wrote:
> Author: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
> 
> The output of MCE banks ownership information on boot tend
> to be long on new processor which has many banks:
> 
>  CPU 1 MCA banks SHD:0 SHD:1 CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:7 SHD:8 
> SHD:9 SHD:12 SHD:13 SHD:14 SHD:15 SHD:16 SHD:17 SHD:18 SHD:19 SHD:20 SHD:21
> 
> This message can fill up the console output when the number
> of cpus is large.
> 
> This patch suppress this info message on boot, and introduce
> debug message in shorter format instead, like:
> 
>  CPU 1 MCE banks map: ssCC PCss ssPP ssss ssss ss
> 
>  where: s: shared, C: checked by cmci, P: checked by poll.
> 
> This patch still keep the info when ownership is updated.
> E.g. if a cpu take over the ownership from hot-removed cpu,
> both message will be shown:
> 
>  CPU 1 MCE banks map updated: CMCI:6 CMCI:7 CMCI:10 CMCI:11
>  CPU 1 MCE banks map: ssCC PCCC ssPP ssCC ssss ss
> 
> v2:
>  - stop changing the level of message on update
>  - change the number of banks message on boot to debug level
> 
> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
> 
>  - Modified to not use pr_cont().
> 
> Signed-off-by: Mike Travis <travis@sgi.com>
> ---
> arch/x86/kernel/cpu/mcheck/mce.c       |    6 +--
> arch/x86/kernel/cpu/mcheck/mce_intel.c |   63 
> +++++++++++++++++++++++++++------
> 2 files changed, 55 insertions(+), 14 deletions(-)
> 
> --- linux.orig/arch/x86/kernel/cpu/mcheck/mce.c
> +++ linux/arch/x86/kernel/cpu/mcheck/mce.c
> @@ -1215,11 +1215,11 @@
> 
>     b = cap & MCG_BANKCNT_MASK;
>     if (!banks)
> -        printk(KERN_INFO "mce: CPU supports %d MCE banks\n", b);
> +        pr_debug("mce: CPU supports %d MCE banks\n", b);
> 
>     if (b > MAX_NR_BANKS) {
> -        printk(KERN_WARNING
> -               "MCE: Using only %u machine check banks out of %u\n",
> +        pr_warning(
> +            "MCE: Using only %u machine check banks out of %u\n",
>             MAX_NR_BANKS, b);
>         b = MAX_NR_BANKS;
>     }
> --- linux.orig/arch/x86/kernel/cpu/mcheck/mce_intel.c
> +++ linux/arch/x86/kernel/cpu/mcheck/mce_intel.c
> @@ -64,14 +64,50 @@
>     mce_notify_irq();
> }
> 
> -static void print_update(char *type, int *hdr, int num)
> +#define    MCE_MSG_LEN    120
> +
> +#ifdef DEBUG_KERNEL
> +static void print_banks_map(int banks, char *buf)
> +{
> +    int i, n;
> +
> +    n = snprintf(buf, MCE_MSG_LEN, "CPU %d MCE banks map:",
> +                            smp_processor_id());
> +    for (i = 0; i < banks; i++) {
> +        n += snprintf(&buf[n], MCE_MSG_LEN - n,
> +            "%s%s", (i % 4) ? "" : " ",
> +            test_bit(i, __get_cpu_var(mce_banks_owned)) ? "C" :
> +            test_bit(i, __get_cpu_var(mce_poll_banks)) ? "P" : "s");
> +    }
> +
> +    /* (indicate if message buffer overflowed) */
> +    pr_debug("%s%s\n", buf, n < MCE_MSG_LEN ? "" : "..." );
> +}
> +
> +static void print_update(char *type, int *hdr, int num, char *buf)
> +{
> +    int n = *hdr;
> +
> +    if (n == 0)
> +        n = snprintf(buf, MCE_MSG_LEN,
> +            "CPU %d MCE banks map updated:", smp_processor_id());
> +
> +    n += snprintf(&buf[n], MCE_MSG_LEN - n, " %s:%d", type, num);
> +    *hdr = n;
> +}
> +
> +#else /* !DEBUG_KERNEL */
> +
> +static inline void print_banks_map(int banks, char *buf)
> +{
> +}
> +
> +static inline void print_update(char *type, int *hdr, int num, char *buf)
> {
> -    if (*hdr == 0)
> -        printk(KERN_INFO "CPU %d MCA banks", smp_processor_id());
> -    *hdr = 1;
> -    printk(KERN_CONT " %s:%d", type, num);
> }
> 
> +#endif
> +
> /*
>  * Enable CMCI (Corrected Machine Check Interrupt) for available MCE banks
>  * on this CPU. Use the algorithm recommended in the SDM to discover shared
> @@ -83,8 +119,10 @@
>     unsigned long flags;
>     int hdr = 0;
>     int i;
> +    char buf[MCE_MSG_LEN];
> 
>     spin_lock_irqsave(&cmci_discover_lock, flags);
> +
>     for (i = 0; i < banks; i++) {
>         u64 val;
> 
> @@ -95,8 +133,8 @@
> 
>         /* Already owned by someone else? */
>         if (val & CMCI_EN) {
> -            if (test_and_clear_bit(i, owned) || boot)
> -                print_update("SHD", &hdr, i);
> +            if (test_and_clear_bit(i, owned) && !boot)
> +                print_update("SHD", &hdr, i, buf);
>             __clear_bit(i, __get_cpu_var(mce_poll_banks));
>             continue;
>         }
> @@ -107,16 +145,19 @@
> 
>         /* Did the enable bit stick? -- the bank supports CMCI */
>         if (val & CMCI_EN) {
> -            if (!test_and_set_bit(i, owned) || boot)
> -                print_update("CMCI", &hdr, i);
> +            if (!test_and_set_bit(i, owned) && !boot)
> +                print_update("CMCI", &hdr, i, buf);
>             __clear_bit(i, __get_cpu_var(mce_poll_banks));
>         } else {
>             WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));
>         }
>     }
> -    spin_unlock_irqrestore(&cmci_discover_lock, flags);
>     if (hdr)
> -        printk(KERN_CONT "\n");
> +        pr_debug("%s%s\n", buf, hdr < MCE_MSG_LEN ? "" : "...");
> +    if (hdr || boot)
> +        print_banks_map(banks, buf);
> +
> +    spin_unlock_irqrestore(&cmci_discover_lock, flags);
> }
> 
> /*