io_queue: Reduce oversized requests warning activity

The submission of oversized request is not a "rare" event, if
it happened once, it will happen again and again, because buffer
sizes in scylla are "static". Not to spam logs with tons of such
warnings, print those only if the oversized request is larger
 than the previous one.

Signed-off-by: Pavel Emelyanov <[email protected]>

src/core/io_queue.cc

@@ -465,13 +465,16 @@ fair_queue_ticket io_queue::request_fq_ticket(const internal::io_request& req, s
         throw std::runtime_error(fmt::format("Unrecognized request passing through I/O queue {}", req.opname()));
     }
 
-    static thread_local logger::rate_limit rate_limit(std::chrono::seconds(30));
+    static thread_local size_t oversize_warning_threshold = 0;
 
     if (size >= _group->_maximum_request_size) {
-        io_log.log(log_level::warn, rate_limit, "oversized request (length {}) submitted. "
+        if (size > oversize_warning_threshold) {
+            oversize_warning_threshold = size;
+            io_log.warn("oversized request (length {}) submitted. "
                 "dazed and confuzed, trimming its weight from {} down to {}", len,
                 size >> request_ticket_size_shift,
                 _group->_maximum_request_size >> request_ticket_size_shift);
+        }
         size = _group->_maximum_request_size;
     }