The patch titled
Avoid too many remote cpu references due to /proc/stat
has been added to the -mm tree. Its filename is
avoid-too-many-remote-cpu-references-due-to-proc-stat.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Avoid too many remote cpu references due to /proc/stat
From: Ravikiran G Thirumalai <kiran@xxxxxxxxxxxx>
Optimize show_stat to collect per-irq information just once.
On x86_64, with newer kernel versions, kstat_irqs is a bit of a problem.
On every call to kstat_irqs, the process brings in per-cpu data from all
online cpus. Doing this for NR_IRQS, which is now 256 + 32 * NR_CPUS
results in (256+32*63) * 63 remote cpu references on a 64 cpu config.
Considering the fact that we already compute this value per-cpu, we can
save on the remote references as below.
Signed-off-by: Alok N Kataria <alok.kataria@xxxxxxxxxxxxxx>
Signed-off-by: Ravikiran Thirumalai <kiran@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/proc_misc.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff -puN fs/proc/proc_misc.c~avoid-too-many-remote-cpu-references-due-to-proc-stat fs/proc/proc_misc.c
--- a/fs/proc/proc_misc.c~avoid-too-many-remote-cpu-references-due-to-proc-stat
+++ a/fs/proc/proc_misc.c
@@ -460,6 +460,11 @@ static int show_stat(struct seq_file *p,
cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
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;
user = nice = system = idle = iowait =
irq = softirq = steal = cputime64_zero;
@@ -477,8 +482,11 @@ static int show_stat(struct seq_file *p,
irq = cputime64_add(irq, kstat_cpu(i).cpustat.irq);
softirq = cputime64_add(softirq, kstat_cpu(i).cpustat.softirq);
steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
- for (j = 0 ; j < NR_IRQS ; j++)
- sum += kstat_cpu(i).irqs[j];
+ for (j = 0; j < NR_IRQS; j++) {
+ unsigned int temp = kstat_cpu(i).irqs[j];
+ sum += temp;
+ per_irq_sum[j] += temp;
+ }
}
seq_printf(p, "cpu %llu %llu %llu %llu %llu %llu %llu %llu\n",
@@ -516,7 +524,7 @@ static int show_stat(struct seq_file *p,
#if !defined(CONFIG_PPC64) && !defined(CONFIG_ALPHA) && !defined(CONFIG_IA64)
for (i = 0; i < NR_IRQS; i++)
- seq_printf(p, " %u", kstat_irqs(i));
+ seq_printf(p, " %u", per_irq_sum[i]);
#endif
seq_printf(p,
@@ -531,6 +539,7 @@ static int show_stat(struct seq_file *p,
nr_running(),
nr_iowait());
+ kfree(per_irq_sum);
return 0;
}
_
Patches currently in -mm which might be from kiran@xxxxxxxxxxxx are
avoid-too-many-remote-cpu-references-due-to-proc-stat.patch
slab-leaks3-default-y.patch
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