rbd: fix bench-write infinite loop

I/O was continously submitted as long as there were few enough ops in
flight. If the number of 'threads' was high, or caching was turned on,
there would never be that many ops in flight, so the loop would continue
indefinitely. Instead, submit at most io_threads ops per offset.

Fixes: #3413
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Sage Weil <sage.weil@inktank.com>

diff --git a/src/rbd.cc b/src/rbd.cc
index f23942c380423b632f2c6eca32348dd65fc77990..833188ae33c17c812c0253b744a378676ed052ba 100644 (file)
--- a/src/rbd.cc
+++ b/src/rbd.cc
@@ -810,11 +810,14 @@ struct rbd_bencher {
       in_flight(0)
   { }
 
-  bool start_write(int max, uint64_t off, uint64_t len, bufferlist& bl) {
-    Mutex::Locker l(lock);
-    if (in_flight >= max)
-      return false;
-    in_flight++;
+  bool start_write(int max, uint64_t off, uint64_t len, bufferlist& bl)
+  {
+    {
+      Mutex::Locker l(lock);
+      if (in_flight >= max)
+       return false;
+      in_flight++;
+    }
     librbd::RBD::AioCompletion *c =
       new librbd::RBD::AioCompletion((void *)this, rbd_bencher_completion);
     image->aio_write(off, len, bl, c);
@@ -869,8 +872,12 @@ static int do_bench_write(librbd::Image& image, uint64_t io_size,
   uint64_t off;
   for (off = 0; off < io_bytes; off += io_size) {
     b.wait_for(io_threads - 1);
-    while (b.start_write(io_threads, off, io_size, bl))
-      ios++;
+    uint64_t i = 0;
+    while (i < io_threads &&
+          b.start_write(io_threads, off, io_size, bl)) {
+      ++i;
+      ++ios;
+    }
 
     utime_t now = ceph_clock_now(NULL);
     utime_t elapsed = now - start;
@@ -884,6 +891,10 @@ static int do_bench_write(librbd::Image& image, uint64_t io_size,
     }
   }
   b.wait_for(0);
+  int r = image.flush();
+  if (r < 0) {
+    cerr << "Error flushing data at the end: " << cpp_strerror(r) << std::endl;
+  }
 
   utime_t now = ceph_clock_now(NULL);
   double elapsed = now - start;