From cd0ee5df307beda0cc8a14af09ffdaafcd5e0e6a Mon Sep 17 00:00:00 2001
From: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Date: Thu, 6 Aug 2020 14:23:01 +0800
Subject: [PATCH 1/4] Add percpu io sq thread support

Add a new IORING_SETUP_SQPOLL_PERCPU flag, this flag is only meaningful
when IORING_SETUP_SQPOLL and IORING_SETUP_SQ_AFF are both specified, that
means if user creates  multiple  io_uring  instances which are all bound
to one same cpu, only a kernel thread is created for this cpu to perform
these io_uring instances' submission queue polling.

Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
---
 man/io_uring_setup.2            | 9 +++++++++
 src/include/liburing/io_uring.h | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/man/io_uring_setup.2 b/man/io_uring_setup.2
index cd69994..30a2306 100644
--- a/man/io_uring_setup.2
+++ b/man/io_uring_setup.2
@@ -147,6 +147,15 @@ is specified. When cgroup setting
 changes (typically in container environment), the bounded cpu set may be
 changed as well.
 .TP
+.B IORING_SETUP_SQPOLL_PERCPU
+This flag is only meaningful when
+.B IORING_SETUP_SQPOLL
+and
+.B IORING_SETUP_SQ_AFF
+are both specified, that means if user creates multiple io_uring instances
+which are all bound to one same cpu, only a kernel thread is created for this
+cpu to perform these io_uring instances' submission queue polling.
+.TP
 .B IORING_SETUP_CQSIZE
 Create the completion queue with
 .IR "struct io_uring_params.cq_entries"
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index a3e0920..d4a0d83 100644
--- a/src/include/liburing/io_uring.h
+++ b/src/include/liburing/io_uring.h
@@ -166,6 +166,8 @@ enum {
  * Only one task is allowed to submit requests
  */
 #define IORING_SETUP_SINGLE_ISSUER	(1U << 12)
+/* use percpu SQ poll thread */
+#define IORING_SETUP_SQPOLL_PERCPU	(1U << 31)
 
 /*
  * Defer running task work to get events.
-- 
2.31.1