Greetings,
Kris Kennaway wrote:
Joseph Koshy wrote:
OK, this is the famous problem with modern CPUs that jkoshy has
declined
to work around :( There are patches for this in perforce, see
http://perforce.freebsd.org/changeView.cgi?CH=126189
"Famous problem" indeed :). I declined the patch because it
is incorrect and incomplete.
I will accept a patch that demonstrates clue about the
workings of the overall system---the changes in the patch
should be safe, complete, should demonstrate that the submitter
has read and understood vendor documentation, should preserve
user experience for naming events, and each supported PMC event
needs to be documented in pmc.3.
I am aware of these issues but repeat my statement that the lack of
working pmc on modern CPUs is causing serious difficulties for our
developer and user base, as witnessed again in this thread.
Kris
Kris do you think the information, that I send you (private email) is
useful ? :)
Also using hwpmc with your patch shows a serious problem with pf and
dynamic rules.
I have desktop PC at home where hwpmc work out of the box, but I'm
running 6.3 on it.
If the information that I send you is not useful, I can spend my weekend
upgrading my desktop PC to RELENG_7_0
and providing new pmc stats, but I have to be sure that developers are
interested in fixing those issues.
I'm willing to invest my time in this, but my skills are not enough to
solve the issues alone, and without help I'll just waste my time.
How hping works is not my biggest problem - for me as I said on few
other mail list the real showstopper is pf and it's keep-state feature.
The interesting part is that both problems point to kernel spending most
of it's time in _mtx_lock_sleep():
pmcstat - pf - during syn flood:
% cumulative self self total
time seconds seconds calls ms/call ms/call name
24.0 268416.00 268416.00 0 100.00% _mtx_lock_sleep [1]
6.7 343572.50 75156.50 0 100.00%
pf_state_compare_ext_gwy [2]
6.7 418405.50 74833.00 0 100.00% pf_src_compare [3]
3.9 462298.50 43893.00 0 100.00%
pf_state_compare_lan_ext [4]
3.6 503019.50 40721.00 0 100.00% pf_test [5]
pmcstat - hping:
% cumulative self self total
time seconds seconds calls ms/call ms/call name
8.6 116120.00 116120.00 0 100.00% _mtx_lock_sleep [1]
5.5 190764.00 74644.00 0 100.00% syscall [2]
3.0 231390.00 40626.00 0 100.00% bpf_mtap [3]
2.9 270334.00 38944.00 0 100.00% Xfast_syscall [4]
2.5 304458.00 34124.00 0 100.00%
bus_dmamap_load_mbuf_sg [5]
2.3 335825.00 31367.00 0 100.00% uma_zalloc_arg [6]
P.S. my desktop PC i single core, but I think I'll find old server with
2x intel p4 CPUs.
--
Best Wishes,
Stefan Lambrev
ICQ# 24134177
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