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| author |   Ravikiran G Thirumalai <kiran@scalex86.org> | 2007-07-19 01:47:53 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-19 10:04:43 -0700 |
| commit | 4004c69ad68dd03733179277280ea2946990ba36 (patch) | |
| tree | 521f206229832f757c0f7652101d187a7a6ff5c8 /fs/proc | |
| parent | gpio calls don't need i/o barriers (diff) | |
| download | linux-dev-4004c69ad68dd03733179277280ea2946990ba36.tar.xz linux-dev-4004c69ad68dd03733179277280ea2946990ba36.zip | |
Avoid too many remote cpu references due to /proc/stat
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@calsoftinc.com>
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/proc_misc.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c index d24b8d46059a..f133afebed7a 100644 --- a/fs/proc/proc_misc.c +++ b/fs/proc/proc_misc.c @@ -445,6 +445,11 @@ static int show_stat(struct seq_file *p, void *v) 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; @@ -462,8 +467,11 @@ static int show_stat(struct seq_file *p, void *v) 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", @@ -501,7 +509,7 @@ static int show_stat(struct seq_file *p, void *v) #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, @@ -516,6 +524,7 @@ static int show_stat(struct seq_file *p, void *v) nr_running(), nr_iowait()); + kfree(per_irq_sum); return 0; } |