linux-kernel - Re: oprofile / selinux / security_port

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Date:	Tue, 27 Mar 2007 09:40:23 -0400
From:	Stephen Smalley <sds@...ho.nsa.gov>
To:	Sami Farin <safari-kernel@...ari.iki.fi>
Cc:	linux-kernel Mailing List <linux-kernel@...r.kernel.org>,
	James Morris <jmorris@...ei.org>,
	Eric Paris <eparis@...isplace.org>
Subject: Re: oprofile / selinux / security_port_sid

On Tue, 2007-03-27 at 13:06 +0300, Sami Farin wrote:
> is there room for improvement in security_port_sid() ?

Yes, lots of room.  Also, it won't get called per-packet if you enable
secmark (echo 0 > /selinux/compat_net or boot with selinux_compat_net=0
or build with SECURITY_SELINUX_ENABLE_SECMARK_DEFAULT), although that
may require updating your policy.

> little test with dns queries (dnsfilter (the client) on local host
> using poll() and dnscache (the server) using epoll (at max 4000 concurrent
> queries):
> (stats for only vmlinux)
> 
> CPU: P4 / Xeon, speed 2797.32 MHz (estimated)
> Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 45000
> Counted FSB_DATA_ACTIVITY events (DRDY or DBSY events on the front side bus) with a unit mask of 0x03 (multiple flags) count 45000
> Counted BRANCH_RETIRED events (retired branches) with a unit mask of 0x05 (multiple flags) count 45000
> Counted BRANCH_RETIRED events (retired branches) with a unit mask of 0x0a (multiple flags) count 45000
> samples  %        samples  %        samples  %        samples  %        symbol name
> 220663   10.2181  6704     17.9737  5735      7.5171  27        1.1989  datagram_poll
> 140086    6.4869  3239      8.6839  3786      4.9624  24        1.0657  sock_poll
> 119636    5.5399  2172      5.8232  7168      9.3954  24        1.0657  do_poll
> 101512    4.7006  3987     10.6893  812       1.0643  14        0.6217  udp_get_port
> 71008     3.2881  1017      2.7266  2694      3.5311  397      17.6288  security_port_sid
> 64350     2.9798  144       0.3861  1912      2.5061  6         0.2664  add_wait_queue
> 60815     2.8161  187       0.5014  3246      4.2546  2         0.0888  remove_wait_queue
> 47456     2.1975  1823      4.8875  476       0.6239  31        1.3766  udp_v4_lookup_longway
> 
> if dnsfilter had used epoll, security_port_sid would
> probably (?) be number one (or two or three) CPU user in kernel.
> 
> also note that 17.6% of mispredicted branches occurr in security_port_sid.
> 
-- 
Stephen Smalley
National Security Agency

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