Messages in this thread | | | Date | Mon, 8 Mar 2004 18:53:54 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] For preventing kstat overflow |
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Kingsley Cheung <kingsley@aurema.com> wrote: > > Hi All, > > What do people think of a patch to change the fields in cpu_usage_stat > from unsigned ints to unsigned long longs? And the same change for > nr_switches in the runqueue structure too?
Sounds unavoidable.
> Its actually worse for context > switches on a busy system, for we've been seeing an average of ten > switches a tick for some of the statistics we have.
Sounds broken. What CPU scheduler are you using?
> for_each_online_cpu(i) { > - seq_printf(p, "cpu%d %u %u %u %u %u %u %u\n", > + seq_printf(p, "cpu%d %llu %llu %llu %llu %llu %llu %llu\n", > i, > - jiffies_to_clock_t(kstat_cpu(i).cpustat.user), > - jiffies_to_clock_t(kstat_cpu(i).cpustat.nice), > - jiffies_to_clock_t(kstat_cpu(i).cpustat.system), > - jiffies_to_clock_t(kstat_cpu(i).cpustat.idle), > - jiffies_to_clock_t(kstat_cpu(i).cpustat.iowait), > - jiffies_to_clock_t(kstat_cpu(i).cpustat.irq), > - jiffies_to_clock_t(kstat_cpu(i).cpustat.softirq)); > + jiffies_64_to_clock_t(kstat_cpu(i).cpustat.user), > + jiffies_64_to_clock_t(kstat_cpu(i).cpustat.nice), > + jiffies_64_to_clock_t(kstat_cpu(i).cpustat.system), > + jiffies_64_to_clock_t(kstat_cpu(i).cpustat.idle), > + jiffies_64_to_clock_t(kstat_cpu(i).cpustat.iowait), > + jiffies_64_to_clock_t(kstat_cpu(i).cpustat.irq), > + jiffies_64_to_clock_t(kstat_cpu(i).cpustat.softirq));
jiffies_64_to_clock_t() takes and returns a u64, not an unsigned long long.
> } > - seq_printf(p, "intr %u", sum); > + seq_printf(p, "intr %llu", sum);
It would be best to convert everything to u64, not to unsigned long long. But cast them to unsigned long long for printk.
It's a bit ugly, but at least it pins everything down to know types and sizes on all architectures.
> struct cpu_usage_stat { > - unsigned int user; > - unsigned int nice; > - unsigned int system; > - unsigned int softirq; > - unsigned int irq; > - unsigned int idle; > - unsigned int iowait; > + unsigned long long user; > + unsigned long long nice; > + unsigned long long system; > + unsigned long long softirq; > + unsigned long long irq; > + unsigned long long idle; > + unsigned long long iowait;
Do these have appropriate locking or are we just accepting the occasional glitch?
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