On Sun, Sep 1, 2013 at 5:32 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Sun, Sep 1, 2013 at 3:01 AM, Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
>>
>> Looks like this is now 10x faster: ~2.66Mloops (debug) VS.
>> ~26.60Mloops (no-debug).
>
> Ok, that's getting to be in the right ballpark.
>
> But your profile is still odd.
>
>> Samples: 159K of event 'cycles:pp', Event count (approx.): 76968896763
>> 12,79% t_lockref_from- [kernel.kallsyms] [k] irq_return
>> 4,36% t_lockref_from- [kernel.kallsyms] [k] __ticket_spin_lock
>
> If you do the profile with "-g", what are the top callers of this? You
> shouldn't see any spinlock load from the path lookup, but you have all
> these other things going on..
>
>> 4,36% t_lockref_from- [kernel.kallsyms] [k] __acct_update_integrals
>> 4,07% t_lockref_from- [kernel.kallsyms] [k] user_exit
>> 3,12% t_lockref_from- [kernel.kallsyms] [k] local_clock
>> 2,83% t_lockref_from- [kernel.kallsyms] [k] lockref_get_or_lock
>> 2,73% t_lockref_from- [kernel.kallsyms] [k] kmem_cache_alloc
>> 2,62% t_lockref_from- [kernel.kallsyms] [k] __d_lookup_rcu
>
> You're spending more time on the task stats than on the actual lookup.
> Maybe you should turn off CONFIG_TASKSTATS..But why that whole
> irq_return thing? Odd.
>
[ init/Kconfig ]
...
config TASKSTATS
bool "Export task/process statistics through netlink"
depends on NET <--- Difficult to disable it?!
default n
help
Export selected statistics for tasks/processes through the
generic netlink interface. Unlike BSD process accounting, the
statistics are available during the lifetime of tasks/processes as
responses to commands. Like BSD accounting, they are sent to user
space on task exit.
Say N if unsure.
...
- Sedat -
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