laforge has submitted this change. (
https://gerrit.osmocom.org/c/libosmocore/+/40489?usp=email )
Change subject: Allow io_uring_submit batching just ahead of poll/select
......................................................................
Allow io_uring_submit batching just ahead of poll/select
Let's add a mode (enabled via the LIBOSMO_IO_URING_BATCH environment
variable), where we don't call io_uring_submit() after every operation
we add to the submission queue. Rather, do that once before we go into
poll.
This should massively reduce the amount of io_uring_enter() syscalls
we're seeing.
Related: OS#6705
Change-Id: Id34fe2ced32c63d15b14810e145744f7509064cc
---
M src/core/osmo_io_uring.c
M src/core/select.c
2 files changed, 47 insertions(+), 4 deletions(-)
Approvals:
pespin: Looks good to me, but someone else must approve
Jenkins Builder: Verified
laforge: Looks good to me, approved
diff --git a/src/core/osmo_io_uring.c b/src/core/osmo_io_uring.c
index b8b240f..347461e 100644
--- a/src/core/osmo_io_uring.c
+++ b/src/core/osmo_io_uring.c
@@ -54,6 +54,11 @@
#define IOFD_URING_ENTRIES 4096
+#define OSMO_IO_URING_BATCH "LIBOSMO_IO_URING_BATCH"
+
+bool g_io_uring_batch = false;
+bool g_io_uring_submit_needed = false;
+
struct osmo_io_uring {
struct osmo_fd event_ofd;
struct io_uring ring;
@@ -88,8 +93,12 @@
/*! initialize the uring and tie it into our event loop */
void osmo_iofd_uring_init(void)
{
+ const char *env;
int rc, evfd;
+ if ((env = getenv(OSMO_IO_URING_BATCH)))
+ g_io_uring_batch = true;
+
rc = io_uring_queue_init(IOFD_URING_ENTRIES, &g_ring.ring, 0);
if (rc < 0)
osmo_panic("failure during io_uring_queue_init(): %s\n",
strerror(-rc));
@@ -117,6 +126,13 @@
}
}
+static inline void iofd_io_uring_submit(void)
+{
+ if (OSMO_LIKELY(!g_io_uring_batch))
+ io_uring_submit(&g_ring.ring);
+ else
+ g_io_uring_submit_needed = true;
+}
static void iofd_uring_submit_recv(struct osmo_io_fd *iofd, enum
iofd_msg_action action)
{
@@ -175,7 +191,8 @@
}
io_uring_sqe_set_data(sqe, msghdr);
- io_uring_submit(&g_ring.ring);
+ iofd_io_uring_submit();
+
/* NOTE: This only works if we have one read per fd */
iofd->u.uring.read_msghdr = msghdr;
}
@@ -317,7 +334,8 @@
OSMO_ASSERT(0);
}
- io_uring_submit(&g_ring.ring);
+ iofd_io_uring_submit();
+
iofd->u.uring.write_msghdr = msghdr;
return 0;
@@ -417,7 +435,8 @@
msghdr->iofd = NULL;
io_uring_prep_cancel(sqe, msghdr, 0);
}
- io_uring_submit(&g_ring.ring);
+
+ iofd_io_uring_submit();
if (IOFD_FLAG_ISSET(iofd, IOFD_FLAG_NOTIFY_CONNECTED)) {
osmo_fd_unregister(&iofd->u.uring.connect_ofd);
@@ -466,7 +485,8 @@
io_uring_prep_writev(sqe, iofd->fd, msghdr->iov, 1, 0);
io_uring_sqe_set_data(sqe, msghdr);
- io_uring_submit(&g_ring.ring);
+ iofd_io_uring_submit();
+
iofd->u.uring.write_msghdr = msghdr;
}
}
@@ -537,4 +557,12 @@
.notify_connected = iofd_uring_notify_connected,
};
+void osmo_io_uring_submit(void)
+{
+ if (OSMO_LIKELY(g_io_uring_submit_needed)) {
+ io_uring_submit(&g_ring.ring);
+ g_io_uring_submit_needed = false;
+ }
+}
+
#endif /* defined(__linux__) */
diff --git a/src/core/select.c b/src/core/select.c
index 70047f0..267f041 100644
--- a/src/core/select.c
+++ b/src/core/select.c
@@ -426,12 +426,22 @@
return work;
}
+#if defined(HAVE_URING)
+void osmo_io_uring_submit(void);
+extern bool g_io_uring_batch;
+#endif
+
static int _osmo_select_main(int polling)
{
unsigned int n_poll;
int rc;
int timeout = 0;
+#if defined(HAVE_URING)
+ if (OSMO_UNLIKELY(g_io_uring_batch))
+ osmo_io_uring_submit();
+#endif
+
/* prepare read and write fdsets */
n_poll = poll_fill_fds();
@@ -464,6 +474,11 @@
int rc;
struct timeval no_time = {0, 0};
+#if defined(HAVE_URING)
+ if (OSMO_UNLIKELY(g_io_uring_batch))
+ osmo_io_uring_submit();
+#endif
+
FD_ZERO(&readset);
FD_ZERO(&writeset);
FD_ZERO(&exceptset);
--
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Gerrit-MessageType: merged
Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Change-Id: Id34fe2ced32c63d15b14810e145744f7509064cc
Gerrit-Change-Number: 40489
Gerrit-PatchSet: 7
Gerrit-Owner: jolly <andr...@eversberg.eu>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: laforge <lafo...@osmocom.org>
Gerrit-Reviewer: pespin <pes...@sysmocom.de>
