Willy Tarreau 7de211c88b MINOR: add a new function call tracer for debugging purposes ... This feature relies on GCC's ability to call helpers at function entry/exit points. We define these helpers to quickly dump the minimum info into a trace file that can be converted to a human readable format using a script in the contrib/trace directory. This has only been implemented in the GNU makefile for now on as it is unsure whether it's supported on all OSes. The feature is enabled by building with "TRACE=1". The performance impact is huge, so this feature should only be used when debugging. To limit the loss of performance, fprintf() has been disabled and the output is hand-crafted and emitted using fwrite(), resulting in doubling the performance. Using the TSC instead of gettimeofday() also doubles the performance. Around 1200 conns/s may be achieved on a Pentium-M 1.7 GHz which leads to around 50 MB/s of traces. The entry and exits of all functions will be dumped into a file designated by the HAPROXY_TRACE environment variable, or by default "trace.out". If the trace file name is empty or "/dev/null", then traces are disabled. If opening the trace file fails, then stderr is used. If HAPROXY_TRACE_FAST is used, then the time is taken from the global <now> variable. Last, if HAPROXY_TRACE_TSC is used, then the machine's TSC is used instead of the real time (almost twice as fast). The output format is : <sec.usec> <level> <caller_ptr> <dir> <callee_ptr> or : <tsc> <level> <caller_ptr> <dir> <callee_ptr> where <dir> is '>' when entering a function and '<' when leaving. The awk script in contrib/trace provides a nicer indented output : 6f74989e6f8 ->->-> run_poll_loop > signal_process_queue [src/haproxy.c:1097:0x804bd69] > [include/proto/signal.h:32:0x8049cd0] 6f74989eb00 run_poll_loop < signal_process_queue [src/haproxy.c:1097:0x804bd69] < [include/proto/signal.h:32:0x8049cd0] 6f74989ef44 ->->-> run_poll_loop > wake_expired_tasks [src/haproxy.c:1100:0x804bd72] > [src/task.c:123:0x8055060] 6f74989f3a6 ->->->-> wake_expired_tasks > eb32_lookup_ge [src/task.c:128:0x8055091] > [ebtree/eb32tree.c:138:0x80a8c70] 6f74989f7e9 wake_expired_tasks < eb32_lookup_ge [src/task.c:128:0x8055091] < [ebtree/eb32tree.c:138:0x80a8c70] 6f74989fc0d ->->->-> wake_expired_tasks > eb32_first [src/task.c:134:0x80550d5] > [ebtree/eb32tree.h:55:0x8054ad0] 6f7498a003d ->->->->-> eb32_first > eb_first [ebtree/eb32tree.h:56:0x8054af1] > [ebtree/ebtree.h:520:0x8054a10] 6f7498a0436 ->->->->->-> eb_first > eb_walk_down [ebtree/ebtree.h:521:0x8054a33] > [ebtree/ebtree.h:442:0x80549a0] 6f7498a0843 ->->->->->->-> eb_walk_down > eb_gettag [ebtree/ebtree.h:445:0x80549d6] > [ebtree/ebtree.h:418:0x80548e0] 6f7498a0c2b eb_walk_down < eb_gettag [ebtree/ebtree.h:445:0x80549d6] < [ebtree/ebtree.h:418:0x80548e0] 6f7498a1042 ->->->->->->-> eb_walk_down > eb_untag [ebtree/ebtree.h:447:0x80549e2] > [ebtree/ebtree.h:412:0x80548a0] 6f7498a1498 eb_walk_down < eb_untag [ebtree/ebtree.h:447:0x80549e2] < [ebtree/ebtree.h:412:0x80548a0] 6f7498a18c6 ->->->->->->-> eb_walk_down > eb_root_to_node [ebtree/ebtree.h:448:0x80549e7] > [ebtree/ebtree.h:432:0x8054960] 6f7498a1cd4 eb_walk_down < eb_root_to_node [ebtree/ebtree.h:448:0x80549e7] < [ebtree/ebtree.h:432:0x8054960] 6f7498a20c4 eb_first < eb_walk_down [ebtree/ebtree.h:521:0x8054a33] < [ebtree/ebtree.h:442:0x80549a0] 6f7498a24b4 eb32_first < eb_first [ebtree/eb32tree.h:56:0x8054af1] < [ebtree/ebtree.h:520:0x8054a10] 6f7498a289c wake_expired_tasks < eb32_first [src/task.c:134:0x80550d5] < [ebtree/eb32tree.h:55:0x8054ad0] 6f7498a2c8c run_poll_loop < wake_expired_tasks [src/haproxy.c:1100:0x804bd72] < [src/task.c:123:0x8055060] 6f7498a3095 ->->-> run_poll_loop > process_runnable_tasks [src/haproxy.c:1103:0x804bd7a] > [src/task.c:190:0x8055150] A nice improvement would possibly consist in trying to get the function's arguments in the stack and to dump a few more infor for some well-known functions (eg: the session's status for process_session).		2012-05-26 00:12:37 +02:00
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trace.awk	MINOR: add a new function call tracer for debugging purposes	2012-05-26 00:12:37 +02:00