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diff --git a/doc/src/performance.html b/doc/src/performance.html deleted file mode 100755 index 9d90acc62..000000000 --- a/doc/src/performance.html +++ /dev/null @@ -1,576 +0,0 @@ -<html> -<head> - <meta http-equiv="Content-Type" content="text/html"> - <title>FreeS/WAN performance</title> - <meta name="keywords" - content="Linux, IPsec, VPN, security, FreeSWAN, performance, benchmark"> - <!-- - - Written by Sandy Harris for the Linux FreeS/WAN project - Freely distributable under the GNU General Public License - - More information at www.freeswan.org - Feedback to users@lists.freeswan.org - - CVS information: - RCS ID: $Id: performance.html,v 1.1 2004/03/15 20:35:24 as Exp $ - Last changed: $Date: 2004/03/15 20:35:24 $ - Revision number: $Revision: 1.1 $ - - CVS revision numbers do not correspond to FreeS/WAN release numbers. - --> -</head> - -<body> -<h1><a name="performance">Performance of FreeS/WAN</a></h1> -The performance of FreeS/WAN is adequate for most applications. - -<p>In normal operation, the main concern is the overhead for encryption, -decryption and authentication of the actual IPsec (<a -href="glossary.html#ESP">ESP</a> and/or <a href="glossary.html#AH">AH</a>) -data packets. Tunnel setup and rekeying occur so much less frequently than -packet processing that, in general, their overheads are not worth worrying -about.</p> - -<p>At startup, however, tunnel setup overheads may be significant. If you -reboot a gateway and it needs to establish many tunnels, expect some delay. -This and other issues for large gateways are discussed <a -href="#biggate">below</a>.</p> - -<h2><a name="pub.bench">Published material</a></h2> - -<p>The University of Wales at Aberystwyth has done quite detailed speed tests -and put <a href="http://tsc.llwybr.org.uk/public/reports/SWANTIME/">their -results</a> on the web.</p> - -<p>Davide Cerri's <a href="http://www.linux.it/~davide/doc/">thesis (in -Italian)</a> includes performance results for FreeS/WAN and for <a -href="glossary.html#TLS">TLS</a>. He posted an <a -href="http://lists.freeswan.org/pipermail/users/2001-December/006303.html">English -summary</a> on the mailing list.</p> - -<p>Steve Bellovin used one of AT&T Research's FreeS/WAN gateways as his -data source for an analysis of the cache sizes required for key swapping in -IPsec. Available as <a -href="http://www.research.att.com/~smb/talks/key-agility.email.txt">text</a> -or <a href="http://www.research.att.com/~smb/talks/key-agility.pdf">PDF -slides</a> for a talk on the topic.</p> - -<p>See also the NAI work mentioned in the next section.</p> - -<h2><a name="perf.estimate">Estimating CPU overheads</a></h2> - -<p>We can come up with a formula that roughly relates CPU speed to the rate -of IPsec processing possible. It is far from exact, but should be usable as a -first approximation.</p> - -<p>An analysis of authentication overheads for high-speed networks, including -some tests using FreeS/WAN, is on the <a -href="http://www.pgp.com/research/nailabs/cryptographic/adaptive-cryptographic.asp">NAI -Labs site</a>. In particular, see figure 3 in this <a -href="http://download.nai.com/products/media/pgp/pdf/acsa_final_report.pdf">PDF -document</a>. Their estimates of overheads, measured in Pentium II cycles per -byte processed are:</p> - -<table border="1" align="center"> - <tbody> - <tr> - <th></th> - <th>IPsec</th> - <th>authentication</th> - <th>encryption</th> - <th>cycles/byte</th> - </tr> - <tr> - <td>Linux IP stack alone</td> - <td>no</td> - <td>no</td> - <td>no</td> - <td align="right">5</td> - </tr> - <tr> - <td>IPsec without crypto</td> - <td>yes</td> - <td>no</td> - <td>no</td> - <td align="right">11</td> - </tr> - <tr> - <td>IPsec, authentication only</td> - <td>yes</td> - <td>SHA-1</td> - <td>no</td> - <td align="right">24</td> - </tr> - <tr> - <td>IPsec with encryption</td> - <td>yes</td> - <td>yes</td> - <td>yes</td> - <td align="right">not tested</td> - </tr> - </tbody> -</table> - -<p>Overheads for IPsec with encryption were not tested in the NAI work, but -Antoon Bosselaers' <a -href="http://www.esat.kuleuven.ac.be/~bosselae/fast.html">web page</a> gives -cost for his optimised Triple DES implementation as 928 Pentium cycles per -block, or 116 per byte. Adding that to the 24 above, we get 140 cycles per -byte for IPsec with encryption.</p> - -<p>At 140 cycles per byte, a 140 MHz machine can handle a megabyte -- 8 -megabits -- per second. Speeds for other machines will be proportional to -this. To saturate a link with capacity C megabits per second, you need a -machine running at <var>C * 140/8 = C * 17.5</var> MHz.</p> - -<p>However, that estimate is not precise. It ignores the differences -between:</p> -<ul> - <li>NAI's test packets and real traffic</li> - <li>NAI's Pentium II cycles, Bosselaers' Pentium cycles, and your machine's - cycles</li> - <li>different 3DES implementations</li> - <li>SHA-1 and MD5</li> -</ul> - -<p>and does not account for some overheads you will almost certainly have:</p> -<ul> - <li>communication on the client-side interface</li> - <li>switching between multiple tunnels -- re-keying, cache reloading and so - on</li> -</ul> - -<p>so we suggest using <var>C * 25</var> to get an estimate with a bit of a -built-in safety factor.</p> - -<p>This covers only IP and IPsec processing. If you have other loads on your -gateway -- for example if it is also working as a firewall -- then you will -need to add your own safety factor atop that.</p> - -<p>This estimate matches empirical data reasonably well. For example, -Metheringham's tests, described <a href="#klips.bench">below</a>, show a 733 -topping out between 32 and 36 Mbit/second, pushing data as fast as it can -down a 100 Mbit link. Our formula suggests you need at least an 800 to handle -a fully loaded 32 Mbit link. The two results are consistent.</p> - -<p>Some examples using this estimation method:</p> - -<table border="1" align="center"> - <tbody> - <tr> - <th colspan="2">Interface</th> - <th colspan="3">Machine speed in MHz</th> - </tr> - <tr> - <th>Type</th> - <th>Mbit per<br> - second</th> - <th>Estimate<br> - Mbit*25</th> - <th>Minimum IPSEC gateway</th> - <th>Minimum with other load - - <p>(e.g. firewall)</p> - </th> - </tr> - <tr> - <td>DSL</td> - <td align="right">1</td> - <td align="right">25 MHz</td> - <td rowspan="2">whatever you have</td> - <td rowspan="2">133, or better if you have it</td> - </tr> - <tr> - <td>cable modem</td> - <td align="right">3</td> - <td align="right">75 MHz</td> - </tr> - <tr> - <td><strong>any link, light load</strong></td> - <td align="right"><strong>5</strong></td> - <td align="right">125 MHz</td> - <td>133</td> - <td>200+, <strong>almost any surplus machine</strong></td> - </tr> - <tr> - <td>Ethernet</td> - <td align="right">10</td> - <td align="right">250 MHz</td> - <td>surplus 266 or 300</td> - <td>500+</td> - </tr> - <tr> - <td><strong>fast link, moderate load</strong></td> - <td align="right"><strong>20</strong></td> - <td align="right">500 MHz</td> - <td>500</td> - <td>800+, <strong>any current off-the-shelf PC</strong></td> - </tr> - <tr> - <td>T3 or E3</td> - <td align="right">45</td> - <td align="right">1125 MHz</td> - <td>1200</td> - <td>1500+</td> - </tr> - <tr> - <td>fast Ethernet</td> - <td align="right">100</td> - <td align="right">2500 MHz</td> - <td rowspan="2" colspan="2" align="center">// not feasible with 3DES in - software on current machines //</td> - </tr> - <tr> - <td>OC3</td> - <td align="right">155</td> - <td align="right">3875 MHz</td> - </tr> - </tbody> -</table> - -<p>Such an estimate is far from exact, but should be usable as minimum -requirement for planning. The key observations are:</p> -<ul> - <li>older <strong>surplus machines</strong> are fine for IPsec gateways at - loads up to <strong>5 megabits per second</strong> or so</li> - <li>a <strong>mid-range new machine</strong> can handle IPsec at rates up - to <strong>20 megabits per second</strong> or more</li> -</ul> - <h3><a name="perf.more">Higher performance alternatives</a></h3> - - <p><a href="glossary.html#AES">AES</a> is a new US government block cipher - standard, designed to replace the obsolete <a - href="glossary.html#DES">DES</a>. If FreeS/WAN using <a - href="glossary.html#3DES">3DES</a> is not fast enough for your application, - the AES <a href="web.html#patch">patch</a> may help.</p> - - <p>To date (March 2002) we have had only one <a - href="http://lists.freeswan.org/pipermail/users/2002-February/007771.html">mailing - list report</a> of measurements with the patch applied. It indicates that, - at least for the tested load on that user's network, <strong>AES roughly - doubles IPsec throughput</strong>. If further testing confirms this, it may - prove possible to saturate an OC3 link in software on a high-end box.</p> - - <p>Also, some work is being done toward support of <a - href="compat.html#hardware">hardware IPsec acceleration</a> which might - extend the range of requirements FreeS/WAN could meet.</p> - - <h3>Other considerations</h3> - - <p>CPU speed may be the main issue for IPsec performance, but of course it - isn't the only one.</p> - - <p>You need good ethernet cards or other network interface hardware to get - the best performance. See this <a - href="http://www.ethermanage.com/ethernet/ethernet.html">ethernet - information</a> page and this <a href="http://www.scyld.com/diag">Linux - network driver</a> page.</p> - - <p>The current FreeS/WAN kernel code is largely single-threaded. It is SMP - safe, and will run just fine on a multiprocessor machine (<a - href="compat.html#multiprocessor">discussion</a>), but the load within the - kernel is not shared effectively. This means that, for example to saturate - a T3 -- which needs about a 1200 MHz machine -- you cannot expect something - like a dual 800 to do the job. </p> - - <p>On the other hand, SMP machines do tend to share loads well so -- - provided one CPU is fast enough for the IPsec work -- a multiprocessor - machine may be ideal for a gateway with a mixed load.</p> - - <h2><a name="biggate">Many tunnels from a single gateway</a></h2> - - <p>FreeS/WAN allows a single gateway machine to build tunnels to many - others. There may, however, be some problems for large numbers as indicated - in this message from the mailing list:</p> - -<pre>Subject: Re: Maximum number of ipsec tunnels? - Date: Tue, 18 Apr 2000 - From: "John S. Denker" <jsd@research.att.com> - -Christopher Ferris wrote: - ->> What are the maximum number ipsec tunnels FreeS/WAN can handle?? - -Henry Spencer wrote: - ->There is no particular limit. Some of the setup procedures currently ->scale poorly to large numbers of connections, but there are (clumsy) ->workarounds for that now, and proper fixes are coming. - -1) "Large" numbers means anything over 50 or so. I routinely run boxes -with about 200 tunnels. Once you get more than 50 or so, you need to worry -about several scalability issues: - -a) You need to put a "-" sign in syslogd.conf, and rotate the logs daily -not weekly. - -b) Processor load per tunnel is small unless the tunnel is not up, in which -case a new half-key gets generated every 90 seconds, which can add up if -you've got a lot of down tunnels. - -c) There's other bits of lore you need when running a large number of -tunnels. For instance, systematically keeping the .conf file free of -conflicts requires tools that aren't shipped with the standard freeswan -package. - -d) The pluto startup behavior is quadratic. With 200 tunnels, this eats up -several minutes at every restart. I'm told fixes are coming soon. - -2) Other than item (1b), the CPU load depends mainly on the size of the -pipe attached, not on the number of tunnels. -</pre> - -<p>It is worth noting that item (1b) applies only to repeated attempts to -re-key a data connection (IPsec SA, Phase 2) over an established keying -connection (ISAKMP SA, Phase 1). There are two ways to reduce this overhead -using settings in <a href="manpage.d/ipsec.conf.5.html">ipsec.conf(5)</a>:</p> -<ul> - <li>set <var>keyingtries</var> to some small value to limit repetitions</li> - <li>set <var>keylife</var> to a short time so that a failing data - connection will be cleaned up when the keying connection is reset.</li> -</ul> - -<p>The overheads for establishing keying connections (ISAKMP SAs, Phase 1) -are lower because for these Pluto does not perform expensive operations -before receiving a reply from the peer.</p> - -<p>A gateway that does a lot of rekeying -- many tunnels and/or low settings -for tunnel lifetimes -- will also need a lot of <a -href="glossary.html#random">random numbers</a> from the random(4) driver.</p> - -<h2><a name="low-end">Low-end systems</a></h2> - -<p><em>Even a 486 can handle a T1 line</em>, according to this mailing list -message:</p> -<pre>Subject: Re: linux-ipsec: IPSec Masquerade - Date: Fri, 15 Jan 1999 11:13:22 -0500 - From: Michael Richardson - -. . . A 486/66 has been clocked by Phil Karn to do -10Mb/s encryption.. that uses all the CPU, so half that to get some CPU, -and you have 5Mb/s. 1/3 that for 3DES and you get 1.6Mb/s....</pre> - -<p>and a piece of mail from project technical lead Henry Spencer:</p> -<pre>Oh yes, and a new timing point for Sandy's docs... A P60 -- yes, a 60MHz -Pentium, talk about antiques -- running a host-to-host tunnel to another -machine shows an FTP throughput (that is, end-to-end results with a real -protocol) of slightly over 5Mbit/s either way. (The other machine is much -faster, the network is 100Mbps, and the ether cards are good ones... so -the P60 is pretty definitely the bottleneck.)</pre> - -<p>From the above, and from general user experience as reported on the list, -it seems clear that a cheap surplus machine -- a reasonable 486, a minimal -Pentium box, a Sparc 5, ... -- can easily handle a home office or a small -company connection using any of:</p> -<ul> - <li>ADSL service</li> - <li>cable modem</li> - <li>T1</li> - <li>E1</li> -</ul> - -<p>If available, we suggest using a Pentium 133 or better. This should ensure -that, even under maximum load, IPsec will use less than half the CPU cycles. -You then have enough left for other things you may want on your gateway -- -firewalling, web caching, DNS and such.</p> - -<h2><a name="klips.bench">Measuring KLIPS</a></h2> - -<p>Here is some additional data from the mailing list.</p> -<pre>Subject: FreeSWAN (specically KLIPS) performance measurements - Date: Thu, 01 Feb 2001 - From: Nigel Metheringham <Nigel.Metheringham@intechnology.co.uk> - -I've spent a happy morning attempting performance tests against KLIPS -(this is due to me not being able to work out the CPU usage of KLIPS so -resorting to the crude measurements of maximum throughput to give a -baseline to work out loading of a box). - -Measurements were done using a set of 4 boxes arranged in a line, each -connected to the next by 100Mbit duplex ethernet. The inner 2 had an -ipsec tunnel between them (shared secret, but I was doing measurements -when the tunnel was up and running - keying should not be an issue -here). The outer pair of boxes were traffic generators or traffic sink. - -The crypt boxes are Compaq DL380s - Uniprocessor PIII/733 with 256K -cache. They have 128M main memory. Nothing significant was running on -the boxes other than freeswan. The kernel was a 2.2.19pre7 patched -with freeswan and ext3. - -Without an ipsec tunnel in the chain (ie the 2 inner boxes just being -100BaseT routers), throughput (measured with ttcp) was between 10644 -and 11320 KB/sec - -With an ipsec tunnel in place, throughput was between 3268 and 3402 -KB/sec - -These measurements are for data pushed across a TCP link, so the -traffic on the wire between the 2 ipsec boxes would have been higher -than this.... - -vmstat (run during some other tests, so not affecting those figures) on -the encrypting box shows approx 50% system & 50% idle CPU - which I -don't believe at all. Interactive feel of the box was significantly -sluggish. - -I also tried running the kernel profiler (see man readprofile) during -test runs. - -A box doing primarily decrypt work showed basically nothing happening - -I assume interrupts were off. -A box doing encrypt work showed the following:- - Ticks Function Load - ~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ - 956 total 0.0010 - 532 des_encrypt2 0.1330 - 110 MD5Transform 0.0443 - 97 kmalloc 0.1880 - 39 des_encrypt3 0.1336 - 23 speedo_interrupt 0.0298 - 14 skb_copy_expand 0.0250 - 13 ipsec_tunnel_start_xmit 0.0009 - 13 Decode 0.1625 - 11 handle_IRQ_event 0.1019 - 11 .des_ncbc_encrypt_end 0.0229 - 10 speedo_start_xmit 0.0188 - 9 satoa 0.0225 - 8 kfree 0.0118 - 8 ip_fragment 0.0121 - 7 ultoa 0.0365 - 5 speedo_rx 0.0071 - 5 .des_encrypt2_end 5.0000 - 4 _stext 0.0140 - 4 ip_fw_check 0.0035 - 2 rj_match 0.0034 - 2 ipfw_output_check 0.0200 - 2 inet_addr_type 0.0156 - 2 eth_copy_and_sum 0.0139 - 2 dev_get 0.0294 - 2 addrtoa 0.0143 - 1 speedo_tx_buffer_gc 0.0024 - 1 speedo_refill_rx_buf 0.0022 - 1 restore_all 0.0667 - 1 number 0.0020 - 1 net_bh 0.0021 - 1 neigh_connected_output 0.0076 - 1 MD5Final 0.0083 - 1 kmem_cache_free 0.0016 - 1 kmem_cache_alloc 0.0022 - 1 __kfree_skb 0.0060 - 1 ipsec_rcv 0.0001 - 1 ip_rcv 0.0014 - 1 ip_options_fragment 0.0071 - 1 ip_local_deliver 0.0023 - 1 ipfw_forward_check 0.0139 - 1 ip_forward 0.0011 - 1 eth_header 0.0040 - 1 .des_encrypt3_end 0.0833 - 1 des_decrypt3 0.0034 - 1 csum_partial_copy_generic 0.0045 - 1 call_out_firewall 0.0125 - -Hope this data is helpful to someone... however the lack of visibility -into the decrypt side makes things less clear</pre> - -<h2><a name="speed.compress">Speed with compression</a></h2> - -<p>Another user reported some results for connections with and without IP -compression:</p> -<pre>Subject: [Users] Speed with compression - Date: Fri, 29 Jun 2001 - From: John McMonagle <johnm@advocap.org> - -Did a couple tests with compression using the new 1.91 freeswan. - -Running between 2 sites with cable modems. Both using approximately -130 mhz pentium. - -Transferred files with ncftp. - -Compressed file was a 6mb compressed installation file. -Non compressed was 18mb /var/lib/rpm/packages.rpm - - Compressed vpn regular vpn -Compress file 42.59 kBs 42.08 kBs -regular file 110.84 kBs 41.66 kBs - -Load was about 0 either way. -Ping times were very similar a bit above 9 ms. - -Compression looks attractive to me.</pre> -Later in the same thread, project technical lead Henry Spencer added: -<pre>> is there a reason not to switch compression on? I have large gateway boxes -> connecting 3 connections, one of them with a measly DS1 link... - -Run some timing tests with and without, with data and loads representative -of what you expect in production. That's the definitive way to decide. -If compression is a net loss, then obviously, leave it turned off. If it -doesn't make much difference, leave it off for simplicity and hence -robustness. If there's a substantial gain, by all means turn it on. - -If both ends support compression and can successfully negotiate a -compressed connection (trivially true if both are FreeS/WAN 1.91), then -the crucial question is CPU cycles. - -Compression has some overhead, so one question is whether *your* data -compresses well enough to save you more CPU cycles (by reducing the volume -of data going through CPU-intensive encryption/decryption) than it costs -you. Last time I ran such tests on data that was reasonably compressible -but not deliberately contrived to be so, this generally was not true -- -compression cost extra CPU cycles -- so compression was worthwhile only if -the link, not the CPU, was the bottleneck. However, that was before the -slow-compression bug was fixed. I haven't had a chance to re-run those -tests yet, but it sounds like I'd probably see a different result. </pre> -The bug he refers to was a problem with the compression libraries that had us -using C code, rather than assembler, for compression. It was fixed before -1.91. - -<h2><a name="methods">Methods of measuring</a></h2> - -<p>If you want to measure the loads FreeS/WAN puts on a system, note that -tools such as top or measurements such as load average are more-or-less -useless for this. They are not designed to measure something that does most -of its work inside the kernel.</p> - -<p>Here is a message from FreeS/WAN kernel programmer Richard Guy Briggs on -this:</p> -<pre>> I have a batch of boxes doing Freeswan stuff. -> I want to measure the CPU loading of the Freeswan tunnels, but am -> having trouble seeing how I get some figures out... -> -> - Keying etc is in userspace so will show up on the per-process -> and load average etc (ie pluto's load) - -Correct. - -> - KLIPS is in the kernel space, and does not show up in load average -> I think also that the KLIPS per-packet processing stuff is running -> as part of an interrupt handler so it does not show up in the -> /proc/stat system_cpu or even idle_cpu figures - -It is not running in interrupt handler. It is in the bottom half. -This is somewhere between user context (careful, this is not -userspace!) and hardware interrupt context. - -> Is this correct, and is there any means of instrumenting how much the -> cpu is being loaded - I don't like the idea of a system running out of -> steam whilst still showing 100% idle CPU :-) - -vmstat seems to do a fairly good job, but use a running tally to get a -good idea. A one-off call to vmstat gives different numbers than a -running stat. To do this, put an interval on your vmstat command -line.</pre> -and another suggestion from the same thread: -<pre>Subject: Re: Measuring the CPU usage of Freeswan - Date: Mon, 29 Jan 2001 - From: Patrick Michael Kane <modus@pr.es.to> - -The only truly accurate way to accurately track FreeSWAN CPU usage is to use -a CPU soaker. You run it on an unloaded system as a benchmark, then start up -FreeSWAN and take the difference to determine how much FreeSWAN is eating. -I believe someone has done this in the past, so you may find something in -the FreeSWAN archives. If not, someone recently posted a URL to a CPU -soaker benchmark tool on linux-kernel.</pre> -</body> -</html> |