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From: Andre Muezerie <andremue@linux.microsoft.com>
To: dev@dpdk.org
Cc: konstantin.ananyev@huawei.com, thomas@monjalon.net,
david.marchand@redhat.com
Subject: [PATCH v17 02/25] eal/linux: remove use of VLAs
Date: Thu, 30 Jan 2025 06:32:18 -0800
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From: Konstantin Ananyev <konstantin.ananyev@huawei.com>
1) ./lib/eal/linux/eal_interrupts.c:1073:16
: warning: ISO C90 forbids variable length array 'events'
MSVC does not support VLAs. Use alloca() to allocate the memory on
the stack.
2) ./lib/eal/linux/eal_interrupts.c:1319:16
: warning: ISO C90 forbids variable length array 'evs'
make eal_epoll_wait() use a fixed size array and use it though multiple
iterations to process up to @maxevents events.
Note that technically it is not one to one replacement, as here we might
reduce number of events returned by first call to epoll_wait(..., timeout);
Signed-off-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>
---
lib/eal/linux/eal_interrupts.c | 32 +++++++++++++++++++++++++++-----
1 file changed, 27 insertions(+), 5 deletions(-)
diff --git a/lib/eal/linux/eal_interrupts.c b/lib/eal/linux/eal_interrupts.c
index 6436f796eb..23039964fc 100644
--- a/lib/eal/linux/eal_interrupts.c
+++ b/lib/eal/linux/eal_interrupts.c
@@ -34,6 +34,8 @@
#define EAL_INTR_EPOLL_WAIT_FOREVER (-1)
#define NB_OTHER_INTR 1
+#define MAX_ITER_EVNUM RTE_EVENT_ETH_INTR_RING_SIZE
+
static RTE_DEFINE_PER_LCORE(int, _epfd) = -1; /**< epoll fd per thread */
/**
@@ -1070,7 +1072,7 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
static void
eal_intr_handle_interrupts(int pfd, unsigned totalfds)
{
- struct epoll_event events[totalfds];
+ struct epoll_event *events = alloca(sizeof(struct epoll_event) * totalfds);
int nfds = 0;
for(;;) {
@@ -1316,8 +1318,9 @@ static int
eal_epoll_wait(int epfd, struct rte_epoll_event *events,
int maxevents, int timeout, bool interruptible)
{
- struct epoll_event evs[maxevents];
int rc;
+ uint32_t i, k, n, num;
+ struct epoll_event evs[MAX_ITER_EVNUM];
if (!events) {
EAL_LOG(ERR, "rte_epoll_event can't be NULL");
@@ -1328,12 +1331,31 @@ eal_epoll_wait(int epfd, struct rte_epoll_event *events,
if (epfd == RTE_EPOLL_PER_THREAD)
epfd = rte_intr_tls_epfd();
+ num = maxevents;
+ n = RTE_MIN(RTE_DIM(evs), num);
+
+ /* Process events in chunks of MAX_ITER_EVNUM */
+
while (1) {
- rc = epoll_wait(epfd, evs, maxevents, timeout);
+ rc = epoll_wait(epfd, evs, n, timeout);
if (likely(rc > 0)) {
+
/* epoll_wait has at least one fd ready to read */
- rc = eal_epoll_process_event(evs, rc, events);
- break;
+ for (i = 0, k = 0; rc > 0;) {
+ k += rc;
+ rc = eal_epoll_process_event(evs, rc,
+ events + i);
+ i += rc;
+
+ /*
+ * try to read more events that are already
+ * available (up to maxevents in total).
+ */
+ n = RTE_MIN(RTE_DIM(evs), num - k);
+ rc = (n == 0) ? 0 : epoll_wait(epfd, evs, n, 0);
+ }
+ return i;
+
} else if (rc < 0) {
if (errno == EINTR) {
if (interruptible)
--
2.47.2.vfs.0.1