From: Sage Weil <sage@redhat.com>
Date: Tue, 17 Jan 2017 16:17:38 +0000 (-0500)
Subject: os/bluestore: prealloc/reserve extent vector for common alloc path
X-Git-Tag: v12.0.0~139^2~3
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=b3fca67cc35cea2889c6ac70ba3541b0048317a4;p=ceph.git

os/bluestore: prealloc/reserve extent vector for common alloc path

No need to worry about the gift/reclaim path--those are very rare.

Signed-off-by: Sage Weil <sage@redhat.com>
---

diff --git a/src/os/bluestore/BlueFS.cc b/src/os/bluestore/BlueFS.cc
index 065ab25c6ad..98c26d23cbd 100644
--- a/src/os/bluestore/BlueFS.cc
+++ b/src/os/bluestore/BlueFS.cc
@@ -1765,6 +1765,7 @@ int BlueFS::_allocate(uint8_t id, uint64_t len,
   }
 
   AllocExtentVector extents;
+  extents.reserve(4);  // 4 should be (more than) enough for most allocations
   int64_t alloc_len = alloc[id]->allocate(left, min_alloc_size, hint,
                           &extents);
   if (alloc_len < (int64_t)left) {
diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index 5e3270a3633..96d5ed2f0a9 100644
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -8105,6 +8105,7 @@ int BlueStore::_do_alloc_write(
     }
 
     AllocExtentVector extents;
+    extents.reserve(4);  // 4 should be (more than) enough for most allocations
     int64_t got = alloc->allocate(final_length, min_alloc_size, max_alloc_size,
                             hint, &extents);
     assert(got == (int64_t)final_length);