Eliminating gettimeofday from construct_reply

[Green, Paul]

Andrew Theurer [mailto:habanero at us.ibm.com] wrote:
> Here is the latest profile:
>   8867 total                                      0.0044
>    700 default_idle                              13.4615
>    689 __generic_copy_to_user                    11.4833
>    419 generic_file_write                         0.2272
>    291 do_softirq                                 1.4265
>    260 fget                                       3.8235
>    250 _text_lock_inode                           1.1521
>  * 241 system_call                                4.3036  *
>    237 qdisc_restart                              0.6237
>    205 schedule                                   0.2330
>    153 d_lookup                                   0.5709
>    145 mod_timer                                  0.6144
>    134 skb_release_data                           1.1552
>    134 ip_queue_xmit                              0.1047
>    132 _text_lock_locks                           0.6600
>    120 tcp_v4_rcv                                 0.0769
>    118 link_path_walk                             0.0530
>    113 kfree                                      0.7847
>    107 tcp_recvmsg                                0.0459
>    105 get_hash_table                             0.6562
>    105 __kfree_skb                                0.3409
>  *  99 do_gettimeofday                            0.8250  *
> 
> *these two are what I am focusing on.   I expect both to be reduced 
> significantly if we can reduce the number of calls to 
> gettimeofday.  I agree, we would need to see at least a few percent
> difference to make this worth while.  I am obviously going to test
> a before/after in any case.

Cool!  Only I don't understand the columns; is the first column a count and
the second column milliseconds per invocation?   Counts aren't all that
interesting, but calculating the percent
of total run time spent by each function would be highly interesting...

PG
--
Paul Green, Senior Technical Consultant, Stratus Technologies.
Day: +1 978-461-7557; FAX: +1 978-461-3610