From: Cathy Zhou <cathy.z...@oracle.com>
iscsi boot performance can be improved by sleep() with finer
grained interval and exponential backoff.
Signed-off-by: Cathy Zhou <cathy.z...@oracle.com>
---
usr/iscsistart.c | 35 ++++++++++++++++++++++++-----------
1 file changed, 24 insertions(+), 11 deletions(-)
diff --git a/usr/iscsistart.c b/usr/iscsistart.c
index 67ac475..1e77e40 100644
--- a/usr/iscsistart.c
+++ b/usr/iscsistart.c
@@ -27,6 +27,7 @@
#include <unistd.h>
#include <string.h>
#include <signal.h>
+#include <time.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include <sys/signal.h>
@@ -224,7 +225,8 @@ static int login_session(struct node_rec *rec)
{
iscsiadm_req_t req;
iscsiadm_rsp_t rsp;
- int rc, retries = 0;
+ int rc, msec, err;
+ struct timespec ts;
rc = apply_params(rec);
if (rc)
@@ -237,18 +239,29 @@ static int login_session(struct node_rec *rec)
req.command = MGMT_IPC_SESSION_LOGIN;
memcpy(&req.u.session.rec, rec, sizeof(*rec));
-retry:
- rc = iscsid_exec_req(&req, &rsp, 0, ISCSID_REQ_TIMEOUT);
/*
- * handle race where iscsid proc is starting up while we are
- * trying to connect.
+ * Need to handle race where iscsid proc is starting up while we are
+ * trying to connect. Retry with exponential backoff, start from 50 ms.
*/
- if (rc == ISCSI_ERR_ISCSID_NOTCONN && retries < 30) {
- retries++;
- sleep(1);
- goto retry;
- } else if (rc)
- iscsi_err_print_msg(rc);
+ for (msec = 50; msec <= 15000; msec <<= 1) {
+ rc = iscsid_exec_req(&req, &rsp, 0, ISCSID_REQ_TIMEOUT);
+ if (rc == 0) {
+ return rc;
+ } else if (rc == ISCSI_ERR_ISCSID_NOTCONN) {
+ ts.tv_sec = msec / 1000;
+ ts.tv_nsec = (msec % 1000) * 1000000L;
+
+ /* On EINTR, retry nanosleep with remaining time. */
+ while ((err = nanosleep(&ts, &ts)) < 0 &&
+ errno == EINTR);
+ if (err < 0)
+ break;
+ } else {
+ break;
+ }
+ }
+
+ iscsi_err_print_msg(rc);
return rc;
}
--
2.17.0
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