Messages in this thread | | | Date | Tue, 23 Sep 2008 23:01:09 +0100 | From | Sitsofe Wheeler <> | Subject | Re: How how latent should non-preemptive scheduling be? |
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Sitsofe Wheeler wrote: > Ingo when you were asking for the ftrace report I presume that would be > for a non preempt kernel (as a preemptive one only showed a very worst > latency of 19657 us in one exceptional case)?
With a non preempt kernel I found the logs would simply become too big without filtering. On Peter's suggestion I used the following to remove the most frequently called functions:
echo acpi_os_release_object > set_ftrace_notrace && echo kmem_cache_* >> set_ftrace_notrace && echo acpi_ut_* >> set_ftrace_notrace
By doing counts across multiple runs I would say that the most frequently called functions are the following (in most frequently called order). The counts are definitely approximate but are reasonable relative to each other.
475325 acpi_os_release_object (acpi_ut_delete_generic_state) 406895 kmem_cache_free (acpi_os_release_object) 402838 kmem_cache_alloc (acpi_ut_create_generic_state) 132968 acpi_ut_update_ref_count (acpi_ut_update_object_reference) 131041 acpi_ut_pop_generic_state (acpi_ut_update_object_reference) 131036 acpi_ut_delete_generic_state (acpi_ut_update_object_reference) 131025 acpi_ut_create_generic_state (acpi_ut_create_update_state) 131023 acpi_ut_create_update_state_and_push (acpi_ut_update_object_reference) 131020 acpi_ut_create_update_state (acpi_ut_create_update_state_and_push) 131018 acpi_ut_push_generic_state (acpi_ut_create_update_state_and_push) 60147 acpi_ns_get_next_node (acpi_ns_delete_namespace_by_owner) 28974 acpi_ns_get_next_valid_node (acpi_ns_get_next_node)
Logs with the filtering on can be seen here (15Mbytes decompressed each): http://sucs.org/~sits/test/eeepc-debug/20080923/latency_trace.gz http://sucs.org/~sits/test/eeepc-debug/20080923/trace.txt.gz
It looks like lots of acpi state is created and deleted...
-- Sitsofe | http://sucs.org/~sits/
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