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    Subject[PATCH 08/14] tracing/filter: Optimize short ciruit check
    From: Steven Rostedt <srostedt@redhat.com>

    The test if we should break out early for OR and AND operations
    can be optimized by comparing the current result with
    (pred->op == OP_OR)

    That is if the result is true and the op is an OP_OR, or
    if the result is false and the op is not an OP_OR (thus an OP_AND)
    we can break out early in either case. Otherwise we continue
    processing.

    Cc: Tom Zanussi <tzanussi@gmail.com>
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
    ---
    kernel/trace/trace_events_filter.c | 12 +++++++++---
    1 files changed, 9 insertions(+), 3 deletions(-)

    diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
    index 1039049..0a3e050 100644
    --- a/kernel/trace/trace_events_filter.c
    +++ b/kernel/trace/trace_events_filter.c
    @@ -426,9 +426,15 @@ int filter_match_preds(struct event_filter *filter, void *rec)
    pred->parent, &move);
    continue;
    case MOVE_UP_FROM_LEFT:
    - /* Check for short circuits */
    - if ((match && pred->op == OP_OR) ||
    - (!match && pred->op == OP_AND)) {
    + /*
    + * Check for short circuits.
    + *
    + * Optimization: !!match == (pred->op == OP_OR)
    + * is the same as:
    + * if ((match && pred->op == OP_OR) ||
    + * (!match && pred->op == OP_AND))
    + */
    + if (!!match == (pred->op == OP_OR)) {
    if (pred == root)
    break;
    pred = get_pred_parent(pred, preds,
    --
    1.7.2.3



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