lock: use spinlock only on multicore systems

Using spinlocks on a single-core system makes usually no meaning,
since as long as the spinlock polling is blocking the only available
CPU core, no other thread can run and since no other thread can run,
the lock won't be unlocked until its time quantum expires and it gets
de-scheduled. In other words, a spinlock wastes CPU time on those
systems for no real benefit. If the thread was put to sleep instead,
another thread could have ran at once, possibly unlocking the lock and
then allowing the first thread to continue processing, once it woke up
again.

Change-Id: I0ffc14e26c2e150b564bcb682a576859ab1d1872
BUG: 1306807
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
Reviewed-on: http://review.gluster.org/13432
Smoke: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>

0 files changed, 0 insertions, 0 deletions