diff options
| author | Prasanna Kumar Kalever <prasanna.kalever@redhat.com> | 2016-02-11 23:45:37 +0530 |
|---|---|---|
| committer | Jeff Darcy <jdarcy@redhat.com> | 2016-03-17 06:55:47 -0700 |
| commit | 7e44c783ad731856956929f6614bbe045c26ea3a (patch) | |
| tree | 85e699cc8926bda7d8bebef63581030817b0eedb /libglusterfs/src/locking.c | |
| parent | fb3d300617d3616e1b901dd5503ff330a542c7be (diff) | |
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>
Diffstat (limited to 'libglusterfs/src/locking.c')
| -rw-r--r-- | libglusterfs/src/locking.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/libglusterfs/src/locking.c b/libglusterfs/src/locking.c new file mode 100644 index 00000000000..d3b9754ef76 --- /dev/null +++ b/libglusterfs/src/locking.c @@ -0,0 +1,28 @@ +/* + Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com> + This file is part of GlusterFS. + + This file is licensed to you under your choice of the GNU Lesser + General Public License, version 3 or any later version (LGPLv3 or + later), or the GNU General Public License, version 2 (GPLv2), in all + cases as published by the Free Software Foundation. +*/ + +#if defined(HAVE_SPINLOCK) +/* None of this matters otherwise. */ + +#include <pthread.h> +#include <unistd.h> + +#define LOCKING_IMPL +#include "locking.h" + +int use_spinlocks = 0; + +static void __attribute__((constructor)) +gf_lock_setup (void) +{ + use_spinlocks = (sysconf(_SC_NPROCESSORS_ONLN) > 1); +} + +#endif |