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unix: handle CQ overflow in iou ring (#3991)

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When there are more than 128 concurrent cq completions the CQ ring
overflows as signaled via the `UV__IORING_SQ_CQ_OVERFLOW`. If this
happens we have to enter the kernel to get the remaining items.
This commit is contained in:
Santiago Gimeno 2023-05-15 10:42:14 +02:00 committed by GitHub
parent 6ad347fae4
commit 30fc896cc1
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 53 additions and 0 deletions
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18
src/unix/linux.c
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@ -159,6 +159,7 @@ enum {
enum {
UV__IORING_SQ_NEED_WAKEUP = 1u,
UV__IORING_SQ_CQ_OVERFLOW = 2u,
};
struct uv__io_cqring_offsets {
@ -891,7 +892,9 @@ static void uv__poll_io_uring(uv_loop_t* loop, struct uv__iou* iou) {
uint32_t tail;
uint32_t mask;
uint32_t i;
uint32_t flags;
int nevents;
int rc;
head = *iou->cqhead;
tail = atomic_load_explicit((_Atomic uint32_t*) iou->cqtail,
@ -931,6 +934,21 @@ static void uv__poll_io_uring(uv_loop_t* loop, struct uv__iou* iou) {
tail,
memory_order_release);
/* Check whether CQE's overflowed, if so enter the kernel to make them
* available. Don't grab them immediately but in the next loop iteration to
* avoid loop starvation. */
flags = atomic_load_explicit((_Atomic uint32_t*) iou->sqflags,
memory_order_acquire);
if (flags & UV__IORING_SQ_CQ_OVERFLOW) {
do
rc = uv__io_uring_enter(iou->ringfd, 0, 0, UV__IORING_ENTER_GETEVENTS);
while (rc == -1 && errno == EINTR);
if (rc < 0)
perror("libuv: io_uring_enter(getevents)"); /* Can't happen. */
}
uv__metrics_inc_events(loop, nevents);
if (uv__get_internal_fields(loop)->current_timeout == 0)
uv__metrics_inc_events_waiting(loop, nevents);

33
test/test-fs.c
View File

@ -662,6 +662,15 @@ static void stat_cb(uv_fs_t* req) {
ASSERT(!req->ptr);
}
static void stat_batch_cb(uv_fs_t* req) {
ASSERT(req->fs_type == UV_FS_STAT || req->fs_type == UV_FS_LSTAT);
ASSERT(req->result == 0);
ASSERT(req->ptr);
stat_cb_count++;
uv_fs_req_cleanup(req);
ASSERT(!req->ptr);
}
static void sendfile_cb(uv_fs_t* req) {
ASSERT(req == &sendfile_req);
@ -4540,3 +4549,27 @@ TEST_IMPL(fs_get_system_error) {
return 0;
}
TEST_IMPL(fs_stat_batch_multiple) {
uv_fs_t req[300];
int r;
int i;
rmdir("test_dir");
r = uv_fs_mkdir(NULL, &mkdir_req, "test_dir", 0755, NULL);
ASSERT_EQ(r, 0);
loop = uv_default_loop();
for (i = 0; i < (int) ARRAY_SIZE(req); ++i) {
r = uv_fs_stat(loop, &req[i], "test_dir", stat_batch_cb);
ASSERT_EQ(r, 0);
}
uv_run(loop, UV_RUN_DEFAULT);
ASSERT_EQ(stat_cb_count, ARRAY_SIZE(req));
MAKE_VALGRIND_HAPPY(loop);
return 0;
}

2
test/test-list.h
View File

@ -384,6 +384,7 @@ TEST_DECLARE (fs_futime)
TEST_DECLARE (fs_lutime)
TEST_DECLARE (fs_file_open_append)
TEST_DECLARE (fs_statfs)
TEST_DECLARE (fs_stat_batch_multiple)
TEST_DECLARE (fs_stat_missing_path)
TEST_DECLARE (fs_read_bufs)
TEST_DECLARE (fs_read_file_eof)
@ -1070,6 +1071,7 @@ TASK_LIST_START
TEST_ENTRY (fs_fd_hash)
#endif
TEST_ENTRY (fs_statfs)
TEST_ENTRY (fs_stat_batch_multiple)
TEST_ENTRY (fs_stat_missing_path)
TEST_ENTRY (fs_read_bufs)
TEST_ENTRY (fs_read_file_eof)