From a90aa4fd2637af482451d20b301e86081ff74297 Mon Sep 17 00:00:00 2001
From: Shiqing Gao <shiqing.gao@intel.com>
Date: Fri, 27 Oct 2023 18:28:54 +0800
Subject: [PATCH] dm: iothread: rename the thread for better readability

This patch renames the iothread for better readability. For instance,
the new name of the iothread for virtio-blk device looks like `iothr-0-blk9:0`.

It could be helpful when tuning the performance and the CPU utilization.

v1 -> v2:
 * add `const` qualifier for the input parameter of `iothread_create`

Tracked-On: #8612

Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>
---
 devicemodel/core/iothread.c              | 15 +++++++++------
 devicemodel/hw/pci/virtio/virtio_block.c |  7 ++++++-
 devicemodel/include/iothread.h           | 11 ++++++++++-
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/devicemodel/core/iothread.c b/devicemodel/core/iothread.c
index 5bc72096a..fb43f1aa8 100644
--- a/devicemodel/core/iothread.c
+++ b/devicemodel/core/iothread.c
@@ -63,7 +63,6 @@ io_thread(void *arg)
 static int
 iothread_start(struct iothread_ctx *ioctx_x)
 {
-	char tname[MAXCOMLEN + 1];
 	pthread_mutex_lock(&ioctx_x->mtx);
 
 	if (ioctx_x->started) {
@@ -78,10 +77,9 @@ iothread_start(struct iothread_ctx *ioctx_x)
 	}
 
 	ioctx_x->started = true;
-	snprintf(tname, sizeof(tname), "iothread_%d", ioctx_x->idx);
-	pthread_setname_np(ioctx_x->tid, tname);
+	pthread_setname_np(ioctx_x->tid, ioctx_x->name);
 	pthread_mutex_unlock(&ioctx_x->mtx);
-	pr_info("iothread_%d started\n", ioctx_x->idx);
+	pr_info("%s started\n", ioctx_x->name);
 
 	return 0;
 }
@@ -158,7 +156,7 @@ iothread_deinit(void)
 			ioctx_x->epfd = -1;
 		}
 		pthread_mutex_destroy(&ioctx_x->mtx);
-		pr_info("iothread_%d stop \n", i);
+		pr_info("%s stop \n", ioctx_x->name);
 	}
 	ioctx_active_cnt = 0;
 	pthread_mutex_unlock(&ioctxes_mutex);
@@ -169,7 +167,7 @@ iothread_deinit(void)
  * Return NULL if fails. Otherwise, return the base of those iothread context instances.
  */
 struct iothread_ctx *
-iothread_create(int ioctx_num)
+iothread_create(int ioctx_num, const char *ioctx_tag)
 {
 	pthread_mutexattr_t attr;
 	int i, ret, base, end;
@@ -199,6 +197,11 @@ iothread_create(int ioctx_num)
 			ioctx_x->started = false;
 			ioctx_x->epfd = epoll_create1(0);
 
+			if (snprintf(ioctx_x->name, PTHREAD_NAME_MAX_LEN,
+				"iothr-%d-%s", ioctx_x->idx, ioctx_tag) >= PTHREAD_NAME_MAX_LEN) {
+				pr_err("%s: iothread name too long \n", __func__);
+			}
+
 			if (ioctx_x->epfd < 0) {
 				ret = -1;
 				pr_err("%s: failed to create epoll fd, error is %d\r\n",
diff --git a/devicemodel/hw/pci/virtio/virtio_block.c b/devicemodel/hw/pci/virtio/virtio_block.c
index 0deb79aba..8c5182a93 100644
--- a/devicemodel/hw/pci/virtio/virtio_block.c
+++ b/devicemodel/hw/pci/virtio/virtio_block.c
@@ -469,6 +469,7 @@ virtio_blk_init(struct vmctx *ctx, struct pci_vdev *dev, char *opts)
 {
 	bool dummy_bctxt;
 	char bident[16];
+	char ioctx_tag[16];
 	struct blockif_ctxt *bctxt;
 	char *opts_tmp = NULL;
 	char *opts_start = NULL;
@@ -585,7 +586,11 @@ virtio_blk_init(struct vmctx *ctx, struct pci_vdev *dev, char *opts)
 				num_iothread = num_vqs;
 			}
 
-			ioctx_base = iothread_create(num_iothread);
+			if (snprintf(ioctx_tag, sizeof(ioctx_tag), "blk%s", bident) >= sizeof(ioctx_tag)) {
+				pr_err("%s: virtio-blk ioctx_tag too long \n", __func__);
+			}
+
+			ioctx_base = iothread_create(num_iothread, ioctx_tag);
 			if (ioctx_base == NULL) {
 				pr_err("%s: Fails to create iothread context instance \n", __func__);
 				return -1;
diff --git a/devicemodel/include/iothread.h b/devicemodel/include/iothread.h
index 415030d30..e5b36bfbe 100644
--- a/devicemodel/include/iothread.h
+++ b/devicemodel/include/iothread.h
@@ -9,6 +9,14 @@
 
 #define IOTHREAD_NUM			40
 
+/*
+ * The pthread_setname_np() function can be used to set a unique name for a thread,
+ * which can be useful for debugging multithreaded applications.
+ * The thread name is a meaningful C language string,
+ * whose length is restricted to 16 characters, including the terminating null byte ('\0').
+ */
+#define PTHREAD_NAME_MAX_LEN		16
+
 struct iothread_mevent {
 	void (*run)(void *);
 	void *arg;
@@ -21,6 +29,7 @@ struct iothread_ctx {
 	bool started;
 	pthread_mutex_t mtx;
 	int idx;
+	char name[PTHREAD_NAME_MAX_LEN];
 };
 
 struct iothreads_info {
@@ -31,6 +40,6 @@ struct iothreads_info {
 int iothread_add(struct iothread_ctx *ioctx_x, int fd, struct iothread_mevent *aevt);
 int iothread_del(struct iothread_ctx *ioctx_x, int fd);
 void iothread_deinit(void);
-struct iothread_ctx *iothread_create(int ioctx_num);
+struct iothread_ctx *iothread_create(int ioctx_num, const char *ioctx_tag);
 
 #endif