Re: [PATCH 08/42] introduce nr_irqs

[Yinghai Lu]

On Sat, Aug 9, 2008 at 2:38 PM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> "Yinghai Lu" <yhlu.kernel@xxxxxxxxx> writes:
>
>> On Sat, Aug 9, 2008 at 9:02 AM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>>> "Yinghai Lu" <yhlu.kernel@xxxxxxxxx> writes:
>>>
>>>>> Also, what's the point, if it's just a renaming?
>>>>
>>>> that is the start point.
>>>> nr_irqs is variable, and will be probed later. and use that number to
>>>> init dyn_alloc.
>>>
>>> YH.
>>>
>>> In my conception the code in kernel/irq.c that today does:
>>>
>>> struct irq_desc *desc;
>>> if (irq >= NR_IRQS)
>>>   return -EINVAL;
>>> desc = irq_desc + irq;
>>>
>>> Should become:
>>>
>>> struct irq_desc *desc;
>>> desc = irq_desc(irq);
>>> if (!desc)
>>>   return -EINVAL;
>>>
>>
>> OK.
>>
>> also want to introduce dummy
>> struct irq_desc
>> {
>>    unsigned int irq;
>> };
>>
>> in linux/interrupt.h if GENERIC_HARDIRQS is not defined.
>> so could have same interface
>> irq_desc()
>> and
>> for_each_irq_desc(irq, desc)
>
> What would use it?  irq_desc doesn't even exist if GENERIC_HARDIRQS are
> not defined.
>
> Far far in the future we may want to introduce an opaque type
> struct irq.  For use with linux/interrupt.h  Allowing things
> like irq_request(struct irq *irq, ...);  For now those kinds
> of interfaces should be internal to the genirq code.

From: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
Date: Fri, 8 Aug 2008 13:56:15 -0700
Subject: [PATCH 31/42] replace loop with nr_irqs for proc/stat

so don't all irq_desc at begining to allocate all.
and only call that when needed

v2: make sure arch without GENERIC_HARDIRQS works too

Signed-off-by: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
---
 fs/proc/proc_misc.c |   50 ++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 36 insertions(+), 14 deletions(-)

Index: linux-2.6/fs/proc/proc_misc.c
===================================================================
--- linux-2.6.orig/fs/proc/proc_misc.c
+++ linux-2.6/fs/proc/proc_misc.c
@@ -495,17 +495,16 @@ static const struct file_operations proc

 static int show_stat(struct seq_file *p, void *v)
 {
-       int i;
+       int i, j;
        unsigned long jif;
        cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
        cputime64_t guest;
        u64 sum = 0;
        struct timespec boottime;
-       unsigned int *per_irq_sum;
-
-       per_irq_sum = kzalloc(sizeof(unsigned int)*nr_irqs, GFP_KERNEL);
-       if (!per_irq_sum)
-               return -ENOMEM;
+       unsigned int per_irq_sum;
+#ifdef CONFIG_GENERIC_HARDIRQS
+       struct irq_desc *desc;
+#endif

        user = nice = system = idle = iowait =
                irq = softirq = steal = cputime64_zero;
@@ -514,8 +513,6 @@ static int show_stat(struct seq_file *p,
        jif = boottime.tv_sec;

        for_each_possible_cpu(i) {
-               int j;
-
                user = cputime64_add(user, kstat_cpu(i).cpustat.user);
                nice = cputime64_add(nice, kstat_cpu(i).cpustat.nice);
                system = cputime64_add(system, kstat_cpu(i).cpustat.system);
@@ -525,10 +522,12 @@ static int show_stat(struct seq_file *p,
                softirq = cputime64_add(softirq, kstat_cpu(i).cpustat.softirq);
                steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
                guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
-               for (j = 0; j < nr_irqs; j++) {
-                       unsigned int temp = kstat_irqs_cpu(j, i);
+               for_each_irq_desc(j, desc)
+               {
+                       unsigned int temp;
+
+                       temp = kstat_irqs_cpu(j, i);
                        sum += temp;
-                       per_irq_sum[j] += temp;
                }
                sum += arch_irq_stat_cpu(i);
        }
@@ -571,8 +570,23 @@ static int show_stat(struct seq_file *p,
        }
        seq_printf(p, "intr %llu", (unsigned long long)sum);

-       for (i = 0; i < nr_irqs; i++)
-               seq_printf(p, " %u", per_irq_sum[i]);
+       /* sum again ? it could be updated? */
+       for_each_irq_desc(j, desc)
+       {
+               per_irq_sum = 0;
+               for_each_possible_cpu(i) {
+                       unsigned int temp;
+
+                       temp = kstat_irqs_cpu(j, i);
+                       per_irq_sum += temp;
+               }
+
+#ifdef CONFIG_HAVE_SPARSE_IRQ
+               seq_printf(p, " %u:%u", j, per_irq_sum);
+#else
+               seq_printf(p, " %u", per_irq_sum);
+#endif
+       }

        seq_printf(p,
                "\nctxt %llu\n"
@@ -586,7 +600,6 @@ static int show_stat(struct seq_file *p,
                nr_running(),
                nr_iowait());

-       kfree(per_irq_sum);
        return 0;
 }

Index: linux-2.6/include/linux/interrupt.h
===================================================================
--- linux-2.6.orig/include/linux/interrupt.h
+++ linux-2.6/include/linux/interrupt.h
@@ -17,6 +17,11 @@

 extern int nr_irqs;

+#ifndef CONFIG_GENERIC_HARDIRQS
+#define for_each_irq_desc(irq, desc)           \
+       for (irq = 0; irq < nr_irqs; irq++])
+#endif
+
 /*
  * These correspond to the IORESOURCE_IRQ_* defines in
  * linux/ioport.h to select the interrupt line behaviour.  When
--
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