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2014-09-05trafgen: Consistently use unsigned int for number of CPUsTobias Klauser1-9/+9
The number of CPUs is stored in ctx.cpus which is unsigned int, so use unsigned int consistently when using CPU number. Negative CPU numbers wont occur anyhow. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-09-01trafgen: Replace variable length arraysTobias Klauser1-6/+9
Use zmalloc()'ed buffer or statically sized array to replace usage of variable sized arrays. Found by the sparse static checker. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-08-21trafgen: minor fix to help text for option "--no-sock-mem"Jesper Dangaard Brouer1-1/+1
Pushed last commit a bit too fast. The help text described that the single letter option for "--no-sock-mem" were "-m", which is wrong the right option is "-A" (only help txt, correct in the code and manual). Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
2014-08-21trafgen: add option to not adjust system socket mem during testrunJesper Dangaard Brouer1-3/+10
The default behavior of trafgen is to boost the systems default socket memory limits during a testrun. This behaviour does not always result in improved performance, because this will stress the kernels SLAB allocators unnecessary. Introducing an option "--no-sock-mem" that instruct trafgen to not perform any socket memory adjustments. Fixes: #130 Acked-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
2014-05-09ring: Merge common ring_{rx,tx} initialization into own functionTobias Klauser1-11/+2
Instead of having to perform the individual steps to initialize a ring and open coding them in multiple places, provide convenience functions to do all at once. This has the nice side effect of allowing to make most of these *_{rx,tx}_ring() functions static in their respective module. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-05-09trafgen: Remove unnecessary initialization of ct.reserve_sizeTobias Klauser1-1/+0
It will be set later on depending on command line option (or panic() out) and it is initialized to 0 by a memset() before anyways. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-04-30ring: Consistently use size_t to specify ring sizeTobias Klauser1-2/+4
The mm_len member of struct ring is of type size_t, but in the code paths leading to set it, unsigned int is used. In circumstances where unsigned int is 32 bit and size_t is 64 bit, this could lead to an integer overflow, which causes an improper ring size being mmap()'ed in mmap_ring_generic(). In order to prevent this, consistently use size_t to store the ring size, since this is also what mmap() takes as its `length' parameter. This now allows to specify ring sizes larger than 4 GiB for both netsniff-ng and trafgen (fixes #90). Reported-by: Jon Schipp <jonschipp@gmail.com> Reported-by: Michał Purzyński <michalpurzynski1@gmail.com> Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-04-30trafgen: Don't expose -k/--kernel-pull anymore and warn if it still usedTobias Klauser1-3/+3
The -k/--kernel-pull option got useless with commit c139e80 ("trafgen: remove timer-based trigger model"). Instead of entirely removing it and thus possibly breaking people's scripts, still accept it as an option, but warn the user about it. We might want to remove the option in a future release. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-04-30trafgen: Use strtoul() instead of strtol() for unsigned longTobias Klauser1-1/+1
If setting an unsigned long variable, use strtoul() instead of strtol(). Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-04-27trafgen: performance regression at 10G due to smaller ring buffer sizeJesper Dangaard Brouer1-1/+1
commit c10621e ("trafgen: keep a small initial ring buffer size to reduce cache-misses") reduced default ring buffer size to 196KiB, but on my big machines with 10Gbit/s this size is too small. Increase default ring-size to 512 KiB, yield the best results, without increasing ring buffer size too much, this fixes #120. Single CPU results from my E5-2630 CPU with intel ixgbe/82599. (Cmd: trafgen --cpp --dev eth8 --conf udp_example01.trafgen --cpu 1) * 769,440 pkts/sec -- default ring-size 196 KiB * 1,417,908 pkts/sec -- ring-size 500 KiB Going above CPUs L3 cache size which is (15Mb) * 1,236,580 pkts/sec -- ring-size 20000KiB The mmap'ed ring buffer is now faster than using sendto(). For comparison, not using the ring-buffer, by using option "-t0": * 1,381,364 (with qdisc bypass) And using the qdisc code path in the kernel (enable via parameter "--qdisc-path") * 1,227,772 pkts/sec (with --qdisc-path) Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
2014-03-26trafgen: keep a small initial ring buffer size to reduce cache-missesDaniel Borkmann1-0/+3
Heavily reduce the initial ring buffer size for trafgen to just 196KiB, so that we can heavily reduce the number of cache-misses related to cache references. People can still overwrite this setting later on via command line option for their specific architecture if they wish. Perhaps the RX_RING should be checked as well in netsniff-ng though the use case there is slightly different. Before: Performance counter stats for 'trafgen -i blub -o dummy0 -n100000000': 137,765,493,346 instructions:k # 0.82 insns per cycle 167,438,826,578 cycles:k # 0.000 GHz 59,508,315 branch-misses:k 361 context-switches:k 6 cpu-migrations:k 134,751,541 cache-misses:k # 85.019 % of all cache refs 158,495,358 cache-references:k 755 kmem:kmem_cache_alloc 15.139458202 seconds time elapsed After: Performance counter stats for 'trafgen -i blub -o dummy0 -n100000000': 137,889,782,650 instructions:k # 0.92 insns per cycle 150,239,185,971 cycles:k # 0.000 GHz 71,583,573 branch-misses:k 423 context-switches:k 7 cpu-migrations:k 60,239 cache-misses:k # 0.073 % of all cache refs 82,502,468 cache-references:k 740 kmem:kmem_cache_alloc 12.028787964 seconds time elapsed Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2014-03-26trafgen: remove timer-based trigger modelDaniel Borkmann1-43/+10
perf reports in mmap case a huge number of kmem_cache_alloc's which seem to stem from triggering signals from kernel to user application, against dummy device: Performance counter stats for 'trafgen -i blub -o dummy0 -n100000000 -k100': <-- mmap case 175,837 kmem:kmem_cache_alloc 14.758900522 seconds time elapsed Performance counter stats for 'trafgen -i blub -o dummy0 -n100000000 -k100 -t0': <-- non-mmap case 707 kmem:kmem_cache_alloc 15.591667364 seconds time elapsed It seems not to case significant number of cache-misses, but it's better to switch to a direct trigger when we cannot fill new frames anymore. After this patch, we see a similar number of kmem_cache_alloc's as in the non-mmap case. This basically renders the kpull interval useless, we can optionally remove it if we don't care about people's scripts. ;-) Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2014-02-22trafgen: Exit gracefully for all possible termination signalsTobias Klauser1-0/+4
Handle all termination signals that we're allowed to handle (SIGKILL can't be handled) in order to exit gracefully in any regular termination case. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2014-02-02trafgen: Don't modify optarg/argvTobias Klauser1-1/+0
Follow commit bed9b6bb ("netsniff-ng: Don't modify optarg/argv"). We shouldn't modify optarg (and thus argv) since it's e.g. used to display the commandline string in `ps'. Since strtoul() reads until it encounters the first non-numeric character and ignores the rest, we can just revert from setting a NULL byte after the numeric part of the string. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-12-12trafgen: take advantage of PACKET_QDISC_BYPASS sock optionJesper Dangaard Brouer1-2/+11
Since Linux 3.14, the kernel supports a socket option PACKET_QDISC_BYPASS, which trafgen enables by default. That allow us to bypass the kernels normal qdisc (traffic control) layer. An option -q, --qdisc-path is added to allow enabling the qdisc path explicity, useful for testing purposes. This will be avail in kernels >= 3.14 via commit d346a3fae3 (packet: introduce PACKET_QDISC_BYPASS socket option). Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
2013-12-11trafgen: speedup TX only path by avoiding kernel packet_rcv() callJesper Dangaard Brouer1-1/+1
The tool trafgen is used in a pktgen style transmit only scenario. We discovered a performance bottleneck in the kernel, when running trafgen, where the kernel stalled on a lock in packet_rcv(). This call is unnecessary for trafgen given its transmit only nature. This packet_rcv() call can, easily be avoided by instructing the RAW/PF_PACKET socket, to not listen to any protocols (by passing protocol argument zero, when creating the socket). The performance gain is huge, increasing performance from approx max 2Mpps to 12Mpps, basically causing trafgen to scale with the number of CPUs. Following tests were run on a 2xCPU E5-2650 with Intel 10Gbit/s ixgbe: Trafgen using sendto() syscall via parameter -t0: * # CPUs -- *with* -- *without* packet_rcv() call * 1 CPU == 1,232,244 -- 1,236,144 pkts/sec * 2 CPUs == 1,592,720 -- 2,593,620 pkts/sec * 3 CPUs == 1,635,623 -- 3,692,216 pkts/sec * 4 CPUs == 1,567,768 -- 4,102,866 pkts/sec * 5 CPUs == 1,700,270 -- 5,151,489 pkts/sec * 6 CPUs == 1,762,392 -- 6,124,512 pkts/sec * 7 CPUs == 1,850,139 -- 7,120,496 pkts/sec * 8 CPUs == 1,770,909 -- 8,058,710 pkts/sec * 9 CPUs == 1,721,072 -- 8,963,192 pkts/sec * 10 CPUs == 1,359,157 -- 9,584,535 pkts/sec * 11 CPUs == 1,175,520 -- 10,498,038 pkts/sec * 12 CPUs == 1,075,867 -- 11,189,292 pkts/sec * 13 CPUs == 1,012,602 -- 12,048,836 pkts/sec * [...] * 20 CPUs == 1,030,446 -- 11,202,449 pkts/sec Trafgen using mmap() TX tpacket_v2 (default) * # CPUs -- *with* -- *without* packet_rcv() call * 1 CPU == 920,682 -- 927,984 pkts/sec * 2 CPUs == 1,607,940 -- 2,061,406 pkts/sec * 3 CPUs == 1,668,488 -- 2,979,463 pkts/sec * 4 CPUs == 1,423,066 -- 3,169,565 pkts/sec * 5 CPUs == 1,507,708 -- 3,910,756 pkts/sec * 6 CPUs == 1,555,616 -- 4,625,844 pkts/sec * 7 CPUs == 1,560,961 -- 5,298,441 pkts/sec * 8 CPUs == 1,596,092 -- 6,000,465 pkts/sec * 9 CPUs == 1,575,139 -- 6,722,130 pkts/sec * 10 CPUs == 1,311,676 -- 7,114,202 pkts/sec * 11 CPUs == 1,157,650 -- 7,859,399 pkts/sec * 12 CPUs == 1,060,366 -- 8,491,004 pkts/sec * 13 CPUs == 1,012,956 -- 9,269,761 pkts/sec * [...] * 20 CPUs == 955,716 -- 8,653,947 pkts/sec It is fairly strange that the mmap() version runs slower than the sendto() version. This is likely another performance problem related to mmap() which seems worth fixing. Note, that the mmap() version speed can be improved by reducing the default --ring-size to around 1-2 MiB. But this does not fix general trend with mmap() performance. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
2013-11-25trafgen: inherit netsniff-ng's -H -Q optionsDaniel Borkmann1-3/+21
Also make these options available to trafgen. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-11-18trafgen: don't bother about device going down, just continue sendingDaniel Borkmann1-2/+2
If we loose carrier, don't bother about panic'ing, but continue sending! Only exit in case we're doing a smoke test. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-10-15trafgen: set interpacket gap in time units (s/ms/us/ns)Jon Schipp1-11/+39
Add ability to set IGP in time units in seconds, milliseconds, microseconds, and nanoseconds by appending a postfix to --gap e.g. --gap 100ms. Also, update the man page and trafgen.zsh to reflect the changes. [Fix whitespaces, coding style and minor wording changes -- tklauser] Signed-off-by: Jon Schipp <jonschipp@gmail.com> Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-09-23trafgen: remove inner loopDaniel Borkmann1-31/+31
Get rid of inner loop in fast path. This simplifies code and readability. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-09-12trafgen: combine likely conditionsDaniel Borkmann1-2/+2
Combine multiple likely conditions into one. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-08-12trafgen: Fix compiler warningsTobias Klauser1-17/+21
Fix the following compiler warnings that occur when building with "-W -Wall -Wextra": trafgen.c: In function ‘timer_elapsed’: trafgen.c:136:31: warning: unused parameter ‘number’ [-Wunused-parameter] trafgen.c: In function ‘apply_csum16’: trafgen.c:346:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c: In function ‘dump_trafgen_snippet’: trafgen.c:415:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c: In function ‘xmit_smoke_probe’: trafgen.c:490:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:506:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:509:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:512:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c: In function ‘__wait_and_sum_others’: trafgen.c:721:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c: In function ‘__correct_global_delta’: trafgen.c:743:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:761:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c: In function ‘xmit_packet_precheck’: trafgen.c:797:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:816:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c: In function ‘main_loop’: trafgen.c:837:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c: In function ‘main’: trafgen.c:1047:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:1065:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:1078:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] trafgen.c:1090:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-08-09mac80211.c: Remove or mark unused function parametersTobias Klauser1-1/+1
Compiling with "-W -Wall -Wextra" reveals the following warnings in mac80211.c: mac80211.c: In function ‘nl80211_init’: mac80211.c:78:67: warning: unused parameter ‘device’ [-Wunused-parameter] mac80211.c: In function ‘nl80211_wait_handler’: mac80211.c:106:48: warning: unused parameter ‘msg’ [-Wunused-parameter] mac80211.c: In function ‘nl80211_error_handler’: mac80211.c:115:54: warning: unused parameter ‘nla’ [-Wunused-parameter] mac80211.c:117:12: warning: unused parameter ‘arg’ [-Wunused-parameter] mac80211.c: In function ‘nl80211_del_mon_if’: mac80211.c:181:72: warning: unused parameter ‘device’ [-Wunused-parameter] Fix them by either marking them as unused (where we need to conform to library APIs or remove them alltogether (for our own APIs). For the function leave_rfmon_mac80211() the according users (netsniff-ng and trafgen) are also changed. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-08-02trafgen: Remove unused local variable in apply_*() functions.Tobias Klauser1-25/+22
The variable `i' in apply_counter(), apply_randomizer() and apply_csum16() is only set once, so use the original parameter `counter_id' instead. Rename `counter_id' to `id' in order to keep it short. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-07-13trafgen: switch for skipping cpu time statistics on exitDaniel Borkmann1-3/+8
For systems with >8 CPUs it might be i) annoying or ii) uninteresting to print CPU time statistics. So introduce a switch that can skip this at exit. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-07-13sparse: netsniff-ng, trafgen: fix remaining time(0) warningsDaniel Borkmann1-1/+1
Those are the last occurences of warnings like: netsniff-ng.c:697:48: warning: Using plain integer as NULL pointer netsniff-ng.c:726:48: warning: Using plain integer as NULL pointer ... Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-07-13trafgen: setup_shared_var: fix reamaindersDaniel Borkmann1-4/+3
Commit bf9232fb6 ("trafgen: setup_shared_var: fix couple of things") forgot to amend the remaining changes in 'len' usage. So lets fix them right now. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-07-13trafgen: sparse: make seed staticDaniel Borkmann1-4/+4
sparse reported that the variable seed can be made static: trafgen.c:110:14: warning: symbol 'seed' was not declared. Should it be static? While at it, also rename a local variable 'seed' to not overlap contexts. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-07-13trafgen: setup_shared_var: fix couple of thingsDaniel Borkmann1-5/+6
1) Fix a couple of sparse warnings: trafgen.c:382:27: error: cannot size expression trafgen.c:391:33: error: cannot size expression trafgen.c:393:33: error: cannot size expression trafgen.c:401:25: error: cannot size expression 2) Use MAP_FAILED instead of (void *) -1 3) No need to cast to void * on mmap(2) 4) Use NULL instead of 0 as mmap(2)'s first argument Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-07-09all: show git id in --version informationDaniel Borkmann1-2/+4
In order to be able to better track regressions or to give support, let us track the Git id as well in version information. This makes the ``--version'' switch actually useful. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-15trafgen: fix checksumming in trafgen example configDaniel Borkmann1-1/+1
Took quite a while to git bisect the cause for the wrong TCP checksum in the -e example. It turned out that commit bf43e1993c7037 ("trafgen: lexer: return original string if no shellcode") "broke" it, since before that commit the TCP checksum from -e example was correct and afterwards not anymore. Well, it didn't break it. What was happening here is that with this fix above, the packet got 1 byte longer since the first character of the example string is not omitted anymore, therefore the checksum got wrong. Fix this by fixing the IP total length of the packet in the -e and man page example. The UDP example from the man page still works well if csumudp() is used, so not affected of this. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-15trafgen: check offsets for all kind of csumsDaniel Borkmann1-2/+5
It seems not critical at this point, but lets check it for all offsets here as well, and mark this check as unlikely to happen. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-15trafgen: fix -n1 bug for packet schedulingDaniel Borkmann1-2/+2
In the current situation, it can happen when we set -n1, that no packet at all will be scheduled. This is due to the case that nearbyint() will for e.g. 2 cpus round to 0 each, and since in __correct_global_delta() we only correct a total delta when a particular CPU is allowed to tx packets (means already has a num > 0), then we correct the delta on the first such CPU. Switch to using round(), so that on 0.5 it will be round to the next higher int, and fix the check to >= 0 in __correct_global_delta() so that a CPU could also get a 0 share of packets. I did a couple of tests with different -n params and cpu(..) configs and this seems to fix that. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04xutils: eliminate xutils, move rest to epoll2Daniel Borkmann1-1/+2
Finally eliminate xutils.{c,h} and move the rest to epoll2. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04timer: add time management functionsDaniel Borkmann1-0/+1
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04sig: add signal handling functionsDaniel Borkmann1-0/+1
Add an extra file for signal handling functions. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04sock: add socket management functionsDaniel Borkmann1-0/+1
Remove them from xutils, and add them to socket management. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04proc: move out process specific management functionsDaniel Borkmann1-0/+1
Move them out of xutils, so that we can maintain them separately. Also simplify things a bit. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04privs: move drop_privileges out of xutilsDaniel Borkmann1-0/+1
Again, also to be able to maintain this more easily. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04xio: rename xio to ioops and reduce its includesDaniel Borkmann1-1/+1
Rename xio to ioops (io-ops) and boil its include files down to a minimum. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04xio: add ioexact operationsDaniel Borkmann1-5/+1
Break this out so that we only need to have sigint non-static where it is really needed. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04cpus: break out cpu related functions from xutilsDaniel Borkmann1-0/+1
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-04xutils: break out string handling and lockingDaniel Borkmann1-0/+2
Break out all string handling functions and lockme stuff in order to further eliminate the big code blob in xutils, so that it can be easier maintained. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-06-03irq: break out from xutils and save + restoreDaniel Borkmann1-0/+2
Break out IRQ functionality from xutils, simplify it, and save + restore IRQ affinity list. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-05-31ring: setup frame structure for v2/v3 in a generic wayDaniel Borkmann1-1/+1
Prepare TPACKET_V3 for allowing to transparently setting up the frame structure such that we do not need to change much in the netsniff-ng/trafgen code. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-05-23make: include build nameDaniel Borkmann1-1/+1
Include long version string into tools when called with --version. Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
2013-05-21trafgen: Remove unnecessary reinitialization of icmp packetTobias Klauser1-2/+0
The entire packet is zeroed using memset() three lines above, thus there is no need to set icmp->code and icmp->checksum to 0 explicitely again. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-05-17trafgen: Add __noreturn attribute previously missedTobias Klauser1-1/+1
The version() function was missed in the previous commit 785fe152 ("trafgen: Add __noreturn attribute to exiting functions"), so add __noreturn to it now. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-05-17trafgen: Add __noreturn attribute to exiting functionsTobias Klauser1-2/+2
Add the __noreturn attribute to all functions which wont return but call die() themselves to exit(). Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
2013-05-15man: trafgen: Minor fixesTobias Klauser1-1/+1
Replace "on default" by "by default", make it a bit more clear what the seed in the -E/--seed option is for and mention exit after display of information on --version and --help. Signed-off-by: Tobias Klauser <tklauser@distanz.ch>