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Date: Sun, 22 Jul 2012 00:47:27 -0700
From: Vijay Subramanian <subramanian.vijay@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH 00/16] Remove the ipv4 routing cache
On 20 July 2012 14:25, David Miller <davem@...emloft.net> wrote:
> On a SPARC-T3 output route lookups are ~876 cycles. Input route
> lookups are ~1169 cycles with rpfilter disabled, and about ~1468
> cycles with rpfilter enabled.
>
> These measurements were taken with the kbench_mod test module in the
> net_test_tools GIT tree:
...
> In fact anyone suitable motivated can just fire up perf on the loading
> of the test net_test_tools benchmark kernel module. I spend much of
> my time going:
>
> bash# perf record insmod ./kbench_mod.ko dst=172.30.42.22 src=74.128.0.1 iif=2
> bash# perf report
>
Dave,
I have been running your routing removal patches for the past 3 days
(upgraded yesterday to latest set including the 17th patch you sent in
response to Eric's comment) and have not seen any issues (crashes
etc).
I used the kbench_mod module in net_test_tools for testing. Averaging
after 16 runs (with 4 samples in each run), I get the following for
output route lookups
(ip_route_output_key):
with route-removal patches: average of 544 cycles with min and max
of 511 and 721
without patches: (commit fa0afcd10 ) : average of 211 cycles with
min and max of 196 and 266
Apart from time spent in fib_table_lookup(), it seems time is also
spent in check_leaf(). I assume this is expected behavior.
Here are 2 sample perf outputs (I have appended the kbench outputs to
each file)
With patches applied:
# ========
# captured on: Sat Jul 21 23:49:43 2012
# hostname : vijaynsu
# os release : 3.5.0-rc7vns+
# perf version : 3.4.13690.gfda9f
# arch : x86_64
# nrcpus online : 8
# nrcpus avail : 8
# cpudesc : Intel(R) Xeon(R) CPU E5320 @ 1.86GHz
# cpuid : GenuineIntel,6,15,11
# total memory : 16407032 kB
# cmdline : /usr/src/net-next/tools/perf/perf record insmod
./kbench_mod.ko dst=172.27.231.128 src=172.27.231.28
# event : name = cycles, type = 0, config = 0x0, config1 = 0x0,
config2 = 0x0, excl_usr = 0, excl_kern = 0, id = { 1, 2, 3, 4, 5, 6,
7, 8 }
# HEADER_CPU_TOPOLOGY info available, use -I to display
# ========
#
# Samples: 458 of event 'cycles'
# Event count (approx.): 209175177
#
# Overhead Command Shared Object Symbol
# ........ ....... ................. .............................
#
40.62% insmod [kernel.kallsyms] [k] fib_table_lookup
24.38% insmod [kernel.kallsyms] [k] __ip_route_output_key
12.33% insmod [kernel.kallsyms] [k] check_leaf
9.29% insmod [kernel.kallsyms] [k] dst_release
6.43% insmod [kernel.kallsyms] [k] __ip_dev_find
2.67% insmod [edac_core] [k] 0x000000000000c1d7
1.33% insmod [kernel.kallsyms] [k] ip_route_output_flow
0.70% insmod [kernel.kallsyms] [k] copy_user_generic_string
0.46% insmod [kernel.kallsyms] [k] path_openat
0.41% insmod [kernel.kallsyms] [k] clear_page_c
0.38% insmod libc-2.11.1.so [.] _dl_addr
0.23% insmod [kernel.kallsyms] [k] native_write_msr_safe
0.22% insmod [kernel.kallsyms] [k] rcu_irq_enter
0.22% insmod [kernel.kallsyms] [k] mem_cgroup_count_vm_event
0.19% insmod [kernel.kallsyms] [k] do_mpage_readpage
0.12% insmod [kernel.kallsyms] [k] math_state_restore
0.02% insmod [kernel.kallsyms] [k] stop_one_cpu
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
Jul 21 23:49:43 vijaynsu kernel: [ 146.382382] kbench:
Jul 21 23:49:43 vijaynsu kernel: [ 146.382382] flow
[IIF(0),OIF(0),MARK(0x00000000),D(172.27.231.128),S(172.27.231.28),TOS(0x00)]
Jul 21 23:49:43 vijaynsu kernel: [ 146.382388] kbench: sizeof(struct
rtable)==176
Jul 21 23:49:43 vijaynsu kernel: [ 146.409943] kbench:
ip_route_output_key tdiff: 546
Jul 21 23:49:43 vijaynsu kernel: [ 146.437490] kbench:
ip_route_output_key tdiff: 546
Jul 21 23:49:43 vijaynsu kernel: [ 146.465064] kbench:
ip_route_output_key tdiff: 511
Jul 21 23:49:43 vijaynsu kernel: [ 146.492615] kbench:
ip_route_output_key tdiff: 672
--------------
Without patches applied : (omitting hardware info)
# Overhead Command Shared Object Symbol
# ........ ....... ................. ............................
#
46.47% insmod [kernel.kallsyms] [k] __ip_route_output_key
17.71% insmod [kernel.kallsyms] [k] dst_release
15.51% insmod [kernel.kallsyms] [k] local_bh_enable
5.92% insmod [kvm] [k] 0x00000000000771ea
4.92% insmod [kernel.kallsyms] [k] local_bh_disable
2.37% insmod [kernel.kallsyms] [k] ip_route_output_flow
1.80% insmod [kernel.kallsyms] [k] clear_page_c
1.32% insmod [kernel.kallsyms] [k] find_get_page
1.31% insmod [kernel.kallsyms] [k] page_remove_rmap
1.15% insmod [kernel.kallsyms] [k] copy_user_generic_string
0.59% insmod [kernel.kallsyms] [k] trace_module_notify
0.59% insmod [kernel.kallsyms] [k] free_pcppages_bulk
0.25% insmod [kernel.kallsyms] [k] __do_fault
0.05% insmod [kernel.kallsyms] [k] wait_for_common
0.02% insmod [kernel.kallsyms] [k] finish_task_switch
0.00% insmod [kernel.kallsyms] [k] native_write_msr_safe
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
Jul 21 23:33:09 vijaynsu kernel: [13465.736545] kbench:
Jul 21 23:33:09 vijaynsu kernel: [13465.736545] flow
[IIF(0),OIF(0),MARK(0x00000000),D(172.27.231.128),S(172.27.231.28),TOS(0x00)]
Jul 21 23:33:09 vijaynsu kernel: [13465.736551] kbench: sizeof(struct
rtable)==216
Jul 21 23:33:09 vijaynsu kernel: [13465.746394] kbench:
ip_route_output_key tdiff: 231
Jul 21 23:33:09 vijaynsu kernel: [13465.756229] kbench:
ip_route_output_key tdiff: 210
Jul 21 23:33:09 vijaynsu kernel: [13465.766062] kbench:
ip_route_output_key tdiff: 196
Jul 21 23:33:09 vijaynsu kernel: [13465.775894] kbench:
ip_route_output_key tdiff: 196
Thanks,
Vijay
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