Re: [RFC PATCH v2 06/20] tracing/filters: Optimise scalar vs cpumask filtering when the user mask is a single CPU
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2023-07-29 19:56:24
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On Thu, 20 Jul 2023 17:30:42 +0100 Valentin Schneider [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Steven noted that when the user-provided cpumask contains a single CPU, then the filtering function can use a scalar as input instead of a full-fledged cpumask. When the mask contains a single CPU, directly re-use the unsigned field predicate functions. Transform '&' into '==' beforehand. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Valentin Schneider <vschneid@redhat.com> --- kernel/trace/trace_events_filter.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 2fe65ddeb34ef..54d642fabb7f1 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c@@ -1750,7 +1750,7 @@ static int parse_pred(const char *str, void *data, * then we can treat it as a scalar input. */ single = cpumask_weight(pred->mask) == 1; - if (single && field->filter_type == FILTER_CPUMASK) { + if (single && field->filter_type != FILTER_CPU) { pred->val = cpumask_first(pred->mask); kfree(pred->mask); }@@ -1761,6 +1761,11 @@ static int parse_pred(const char *str, void *data, FILTER_PRED_FN_CPUMASK; } else if (field->filter_type == FILTER_CPU) { pred->fn_num = FILTER_PRED_FN_CPU_CPUMASK; + } else if (single) { + pred->op = pred->op == OP_BAND ? OP_EQ : pred->op;
Nit, the above can be written as: pred->op = pret->op != OP_BAND ? : OP_EQ; -- Steve
+ pred->fn_num = select_comparison_fn(pred->op, field->size, false);
+ if (pred->op == OP_NE)
+ pred->not = 1;
} else {
switch (field->size) {
case 8: