From db8893838433972feafe545117b60dca8c7318df Mon Sep 17 00:00:00 2001 From: Slavomir Kaslev Date: Wed, 17 Apr 2019 16:09:58 +0300 Subject: [PATCH 1/2] trace-cmd: Optimize how pid filters are expressed 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). Link: http://lore.kernel.org/linux-trace-devel/20190417130959.10064-2-kaslevs@vmware.com Reported-by: Phil Auld Tested-by: Phil Auld Suggested-by: Steven Rostedt (VMware) Signed-off-by: Slavomir Kaslev Signed-off-by: Steven Rostedt (VMware) --- trace-record.c | 117 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 81 insertions(+), 36 deletions(-) diff --git a/trace-record.c b/trace-record.c index 9479f5f8073c..e636c97d701d 100644 --- a/trace-record.c +++ b/trace-record.c @@ -903,10 +903,63 @@ 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 @@ -916,54 +969,46 @@ 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; } -- 2.20.1