Messages in this thread | | | Date | Mon, 25 May 2009 12:50:34 +0200 | From | Martin Schwidefsky <> | Subject | Re: [GIT PULL] cputime patch for 2.6.30-rc6 |
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On Tue, 19 May 2009 11:00:35 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> So, I'm really not objecting too much to the patch at hand, but I'd love > to find a solution to this problem.
It is not hard so solve the problem for /proc/uptime, e.g. like this:
static u64 uptime_jiffies = INITIAL_JIFFIES; static struct timespec ts_uptime; static struct timespec ts_idle;
static int uptime_proc_show(struct seq_file *m, void *v) { cputime_t idletime; u64 now; int i;
now = get_jiffies_64(); if (uptime_jiffies != now) { uptime_jiffies = now; idletime = cputime_zero; for_each_possible_cpu(i) idletime = cputime64_add(idletime, kstat_cpu(i).cpustat.idle); do_posix_clock_monotonic_gettime(&ts_uptime); monotonic_to_bootbased(&ts_uptime); cputime_to_timespec(idletime, &ts_idle); }
seq_printf(m, "%lu.%02lu %lu.%02lu\n", (unsigned long) ts_uptime.tv_sec, (ts_uptime.tv_nsec / (NSEC_PER_SEC / 100)), (unsigned long) ts_idle.tv_sec, (ts_idle.tv_nsec / (NSEC_PER_SEC / 100))); return 0; }
For /proc/stat it is less clear. Just storing the values in static variables is not such a good idea as there are lots of values. 10*NR_CPUS + NR_IRQS values to be exact. With NR_CPUS in the thousands this will waste quite a bit of memory.
I fixed another problem with Michael original patch and added the new one to reduce the frequency of accesses to kstat_cpu for /proc/uptime. You'll find both at:
git://git390.marist.edu/pub/scm/linux-2.6.git cputime
-- blue skies, Martin.
"Reality continues to ruin my life." - Calvin.
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