Add rbdcache max dirty object option

Librbd will calculate max dirty object according to rbd_cache_max_size, it
doesn't suitable for every case. If user set image order 24, the calculating
result is too small for reality. It will increase the overhead of trim call
which is called each read/write op.

Now we make it as option for tunning, by default this value is calculated.

Signed-off-by: Haomai Wang <haomaiwang@gmail.com>
(cherry picked from commit 3c7229a2fea98b30627878c86b1410c8eef2b5d7)

diff --git a/src/common/config_opts.h b/src/common/config_opts.h
index f8dd5f0ed968ffd337a96941e0e30f721a33f9aa..c0679b020c96b679b4faf70fb59232cbea08fac8 100644 (file)
--- a/src/common/config_opts.h
+++ b/src/common/config_opts.h
@@ -713,6 +713,7 @@ OPTION(rbd_cache_size, OPT_LONGLONG, 32<<20)         // cache size in bytes
 OPTION(rbd_cache_max_dirty, OPT_LONGLONG, 24<<20)    // dirty limit in bytes - set to 0 for write-through caching
 OPTION(rbd_cache_target_dirty, OPT_LONGLONG, 16<<20) // target dirty limit in bytes
 OPTION(rbd_cache_max_dirty_age, OPT_FLOAT, 1.0)      // seconds in cache before writeback starts
+OPTION(rbd_cache_max_dirty_object, OPT_INT, 0)       // dirty limit for objects - set to 0 for auto calculate from rbd_cache_size
 OPTION(rbd_cache_block_writes_upfront, OPT_BOOL, false) // whether to block writes to the cache before the aio_write call completes (true), or block before the aio completion is called (false)
 OPTION(rbd_concurrent_management_ops, OPT_INT, 10) // how many operations can be in flight for a management operation like deleting or resizing an image
 OPTION(rbd_balance_snap_reads, OPT_BOOL, false)

diff --git a/src/librbd/ImageCtx.cc b/src/librbd/ImageCtx.cc
index d2f0a4a96b19377cbfe70900225f2540cf7d1811..b5c2db6e7895ee9205f084e73bfbd80399929f8b 100644 (file)
--- a/src/librbd/ImageCtx.cc
+++ b/src/librbd/ImageCtx.cc
@@ -185,10 +185,14 @@ namespace librbd {
 
     // size object cache appropriately
     if (object_cacher) {
-      uint64_t obj = cct->_conf->rbd_cache_size / (1ull << order);
+      uint64_t obj = cct->_conf->rbd_cache_max_dirty_object;
+      if (!obj) {
+        obj = cct->_conf->rbd_cache_size / (1ull << order);
+        obj = obj * 4 + 10;
+      }
       ldout(cct, 10) << " cache bytes " << cct->_conf->rbd_cache_size << " order " << (int)order
                     << " -> about " << obj << " objects" << dendl;
-      object_cacher->set_max_objects(obj * 4 + 10);
+      object_cacher->set_max_objects(obj);
     }
 
     ldout(cct, 10) << "init_layout stripe_unit " << stripe_unit
@@ -587,7 +591,7 @@ namespace librbd {
     cache_lock.Unlock();
     if (unclean) {
       lderr(cct) << "could not release all objects from cache: "
-                << unclean << " bytes remain" << dendl;
+                 << unclean << " bytes remain" << dendl;
       return -EBUSY;
     }
     return r;