Express pid filters as allowed/disallowed filter ranges
(pid>=100&&pid<=103)
instead of specifying them per pid
(pid==100||pid==101||pid==102||pid==103)
This makes the size of the resulting filter smaller (and faster) and avoids
overflowing the filter size limit of one page which we can hit on bigger
machines (say >160 CPUs).
Signed-off-by: Slavomir Kaslev <kaslevs@xxxxxxxxxx>
Reported-by: Phil Auld <pauld@xxxxxxxxxx>
Suggested-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
tracecmd/trace-record.c | 117 +++++++++++++++++++++++++++-------------
1 file changed, 81 insertions(+), 36 deletions(-)
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index a3a34f1..4523128 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -951,10 +951,63 @@ static void update_ftrace_pids(int reset)
static void update_event_filters(struct buffer_instance *instance);
static void update_pid_event_filters(struct buffer_instance *instance);
+static void append_filter_pid_range(char **filter, int *curr_len,
+ const char *field,
+ int start_pid, int end_pid, bool exclude)
+{
+ const char *op = "", *op1, *op2, *op3;
+ int len;
+
+ if (*filter && **filter)
+ op = exclude ? "&&" : "||";
+
+ /* Handle thus case explicitly so that we get `pid==3` instead of
+ * `pid>=3&&pid<=3` for singleton ranges
+ */
+ if (start_pid == end_pid) {
+#define FMT "%s(%s%s%d)"
+ len = snprintf(NULL, 0, FMT, op,
+ field, exclude ? "!=" : "==", start_pid);
+ *filter = realloc(*filter, *curr_len + len + 1);
+ if (!*filter)
+ die("realloc");
+
+ len = snprintf(*filter + *curr_len, len + 1, FMT, op,
+ field, exclude ? "!=" : "==", start_pid);
+ *curr_len += len;
+
+ return;
+#undef FMT
+ }
+
+ if (exclude) {
+ op1 = "<";
+ op2 = "||";
+ op3 = ">";
+ } else {
+ op1 = ">=";
+ op2 = "&&";
+ op3 = "<=";
+ }
+
+#define FMT "%s(%s%s%d%s%s%s%d)"
+ len = snprintf(NULL, 0, FMT, op,
+ field, op1, start_pid, op2,
+ field, op3, end_pid);
+ *filter = realloc(*filter, *curr_len + len + 1);
+ if (!*filter)
+ die("realloc");
+
+ len = snprintf(*filter + *curr_len, len + 1, FMT, op,
+ field, op1, start_pid, op2,
+ field, op3, end_pid);
+ *curr_len += len;
+}
+
/**
* make_pid_filter - create a filter string to all pids against @field
* @curr_filter: Append to a previous filter (may realloc). Can be NULL
- * @field: The fild to compare the pids against
+ * @field: The field to compare the pids against
*
* Creates a new string or appends to an existing one if @curr_filter
* is not NULL. The new string will contain a filter with all pids
@@ -964,54 +1017,46 @@ static void update_pid_event_filters(struct buffer_instance *instance);
*/
static char *make_pid_filter(char *curr_filter, const char *field)
{
+ int start_pid = -1, last_pid = -1;
+ int last_exclude = -1;
struct filter_pids *p;
- char *filter;
- char *orit;
- char *match;
- char *str;
+ char *filter = NULL;
int curr_len = 0;
- int len;
/* Use the new method if possible */
if (have_set_event_pid)
return NULL;
- len = len_filter_pids + (strlen(field) + strlen("(==)||")) * nr_filter_pids;
-
- if (curr_filter) {
- curr_len = strlen(curr_filter);
- filter = realloc(curr_filter, curr_len + len + strlen("(&&())"));
- if (!filter)
- die("realloc");
- memmove(filter+1, curr_filter, curr_len);
- filter[0] = '(';
- strcat(filter, ")&&(");
- curr_len = strlen(filter);
- } else
- filter = malloc(len);
- if (!filter)
- die("Failed to allocate pid filter");
-
- /* Last '||' that is not used will cover the \0 */
- str = filter + curr_len;
+ if (!filter_pids)
+ return curr_filter;
for (p = filter_pids; p; p = p->next) {
- if (p->exclude) {
- match = "!=";
- orit = "&&";
- } else {
- match = "==";
- orit = "||";
+ /*
+ * PIDs are inserted in `filter_pids` from the front and that's
+ * why we expect them in descending order here.
+ */
+ if (p->pid == last_pid - 1 && p->exclude == last_exclude) {
+ last_pid = p->pid;
+ continue;
}
- if (p == filter_pids)
- orit = "";
- len = sprintf(str, "%s(%s%s%d)", orit, field, match, p->pid);
- str += len;
+ if (start_pid != -1)
+ append_filter_pid_range(&filter, &curr_len, field,
+ last_pid, start_pid,
+ last_exclude);
+
+ start_pid = last_pid = p->pid;
+ last_exclude = p->exclude;
+
}
+ append_filter_pid_range(&filter, &curr_len, field,
+ last_pid, start_pid, last_exclude);
- if (curr_len)
- sprintf(str, ")");
+ if (curr_filter) {
+ char *save = filter;
+ asprintf(&filter, "(%s)&&(%s)", curr_filter, filter);
+ free(save);
+ }
return filter;
}
--
2.19.1
|