Messages in this thread |  | | | Date | Sun, 11 Jul 2004 23:37:50 -0700 | | From | Andrew Morton <> | | Subject | Re: [PATCH] Instrumenting high latency |
Con Kolivas <kernel@kolivas.org> wrote: > > Because of the recent discussion about latency in the kernel I asked William > Lee Irwin III to help create some instrumentation to determine where in the > kernel there were still sustained periods of non-preemptible code. He hacked > together this simple patch which times periods according to the preempt > count.
Looks sane.
> The patch appears to require CONFIG_PREEMPT enabled on uniprocessor and is > i386 only at the moment.
Not sure what you mean by "on uniprocessor"? AFAICT the patch will work as-is on uniprocessor and on SMP. Looks like it'll work with CONFIG_PREEMPT=n, too, although that would be a slightly bizarre thing to do.
+ print_symbol("%s\n", + __get_cpu_var(preempt_exit));
I'll change this to
print_symbol("%s", __get_cpu_var(preempt_exit)); printk("\n");
so it doesn't make a mess with CONFIG_KALLSYMS=n.
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