dump: Handle cycles in graphviz #1978
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Identify if the current graph entry must be skipped druing `dump`, which is done during the add_graph_entry() procedure. Basic idea is to find recursive calls, but the first recursive call cannot be skipped. For example, if the call trace shows: main - fib - fib - fib then the first (fib - fib) must be present but the second must be skipped, making the graph look like: main - fib - fib To separate recursive calls from the first recursive call, determine if the node's name is the same with curr and additionally check if curr->parent's name is the same as well. Signed-off-by: Daon Park <[email protected]>
If a node is skipped due to being a recursive call, then it's nr_calls must be correctly appended to the first recursive call. During the `add_graph_entry()` procedure, it looks for the source of the first recursive call and saves it to recursive_src. Next, if the current graph entry node is skipped, then the nr_calls is added to the add_calls_tgt. Signed-off-by: Daon Park <[email protected]>
If a node is marked as True in the skip variable, the dump file will not record that node. Signed-off-by: Daon Park <[email protected]>
During a search for the source of the recursive call, it must check for NULL pointers. This passes the unittest 51 graph_basic. Signed-off-by: Daon Park <[email protected]>
During a search for the destination node for the nr_calls, it must check for NULL pointers. This passes the unittest 52 graph_command. Signed-off-by: Daon Park <[email protected]>
During the determination of a node skip, it must check for NULL pointers in the name. This passes the unittest 105 tui_command. Signed-off-by: Daon Park <[email protected]>
namhyung
reviewed
Oct 31, 2024
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Hello, thanks for your contribution.
First, you don't need to create a new PR for code changes. Just keep the PR and force-push changes to your branch.
Second, Please remove commits to add NULL checks and squash them to the original changes.
Third, I think you modified logic in the general code which will affect other graph codes that might not want to merge recursive calls. If so, you may want to pass an option (or set it globally somewhere) to control the behavior.
| @@ -63,6 +63,7 @@ static int add_graph_entry(struct uftrace_task_graph *tg, char *name, size_t nod | |||
| struct uftrace_graph_node *curr = tg->node; | |||
| struct uftrace_fstack *fstack; | |||
| static uint32_t next_id = 1; | |||
| static bool skip = false; | |||
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I'm not sure if it needs to be 'static'.
| if (name) { | ||
| if (curr && curr->parent) { | ||
| skip = !strcmp(name, curr->name) && !strcmp(name, curr->parent->name); | ||
| } |
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These commits include skipping the recursive calls during the dump of graphviz, and correctly adding number of calls of the skipped entries to the initial recursive call.
Fixed: #1500