On Wed, 17 Apr 2019, Phil Auld wrote:
> On Wed, Apr 17, 2019 at 04:09:58PM +0300 Slavomir Kaslev wrote:
> > 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).
>
> This one works as well :)
>
> I finally hit a case where my trace-cmd pids were non-contiguous and
> this split the range up correctly.
>
>
> FILTER write /sys/kernel/debug/tracing/events/sched/sched_kthread_stop/filter (len 74) value "(common_pid<21420||common_pid>21425)&&(common_pid<21265||common_pid>21418)"
> FILTER write /sys/kernel/debug/tracing/events/sched/sched_kthread_stop_ret/filter (len 74) value "(common_pid<21420||common_pid>21425)&&(common_pid<21265||common_pid>21418)"
> ...
> FILTER write /sys/kernel/debug/tracing/events/sched/sched_switch/filter (len 142) value "(common_pid<21420||common_pid>21425)&&(common_pid<21265||common_pid>21418)||(next_pid<21420||next_pid>21425)&&(next_pid<21265||next_pid>21418)"
It seems crazy that we write "common_pid", instead of "pid" or "cpid", or
something like that.
>
>
> The latter is correct given precendce of && before || but I wonder if () don't make sense? I always have to look
> that one up :)
>
> If I were writing that in code I'd probably put in the extra ()s, but since it's generated and no
> one actually sees it, probably okay and simpler as is.
>
>
> Having seen that and having tried it on a few other machines I'd be more willing to have a
>
> Tested-by: Phil Auld <pauld@xxxxxxxxxx>
>
> on it, if you want it.
>
> Cheers,
> Phil
>
>
> >
> > 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
> >
>
> --
>
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