From 7ad1badac9fba9286aaee0a1e90b6b3c8d32da9d Mon Sep 17 00:00:00 2001
From: Florian Schmaus <flow@cs.fau.de>
Date: Mon, 8 Mar 2021 19:53:48 +0100
Subject: [PATCH] [IO] Use std::array for reapedCompletions
Probably avoids dynamic memory allocation done by the previously used
std::vector.
---
emper/io/IoContext.cpp | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/emper/io/IoContext.cpp b/emper/io/IoContext.cpp
index 8d8aaa31..d1fec427 100644
--- a/emper/io/IoContext.cpp
+++ b/emper/io/IoContext.cpp
@@ -168,11 +168,10 @@ auto IoContext::reapCompletions() -> std::vector<Fiber *> {
uint32_t maxRaceFreeCompleterAttempts = 1;
- using Completion = std::pair<uint32_t, TaggedPtr>;
+ using Completion = std::pair<uint32_t, void *>;
// vector to store seen cqes to make the critical section
// where cq_lock is held as small as possible
- std::vector<Completion> reapedCompletions;
- reapedCompletions.reserve(CQE_BATCH_COUNT);
+ std::array<Completion, CQE_BATCH_COUNT> reapedCompletions;
// Vector returned containing all reaped completions in form of fibers.
std::vector<Fiber *> continuationFibers;
@@ -208,14 +207,10 @@ reap_cqes:
for (unsigned i = 0; i < count; ++i) {
struct io_uring_cqe *cqe = cqes[i];
void *cqe_data = io_uring_cqe_get_data(cqe);
- TaggedPtr tptr(cqe_data);
-
- // Got a CQE for a forgotten Future
- if (!tptr) {
- continue;
- }
- reapedCompletions.emplace_back(cqe->res, tptr);
+ auto &reapedCompletion = reapedCompletions[i];
+ reapedCompletion.first = cqe->res;
+ reapedCompletion.second = cqe_data;
}
io_uring_cq_advance(&ring, count);
@@ -251,11 +246,18 @@ reap_cqes:
stats.record_reaps<callerEnvironment>(count);
- continuationFibers.reserve(reapedCompletions.size());
+ continuationFibers.reserve(count);
- for (auto &completion : reapedCompletions) {
+ for (unsigned i = 0; i < count; ++i) {
+ auto &completion = reapedCompletions[i];
auto res = completion.first;
- auto tptr = completion.second;
+ auto *cqe_data = completion.second;
+
+ TaggedPtr tptr(cqe_data);
+ // Got a CQE for a forgotten Future.
+ if (!tptr) {
+ continue;
+ }
auto tag = static_cast<PointerTags>(tptr.getTag());
switch (tag) {
@@ -305,7 +307,6 @@ reap_cqes:
if (reReap) {
// schedule all already collected continuation fibers
runtime.schedule(continuationFibers.begin(), continuationFibers.end());
- reapedCompletions.clear();
continuationFibers.clear();
goto reap_cqes;
--
GitLab