On Tue, Jun 19, 2018 at 10:24:44AM +0200, Thomas Hellstrom wrote: > The current Wound-Wait mutex algorithm is actually not Wound-Wait but > Wait-Die. Implement also Wound-Wait as a per-ww-class choice. Wound-Wait > is, contrary to Wait-Die a preemptive algorithm and is known to generate > fewer backoffs. Testing reveals that this is true if the > number of simultaneous contending transactions is small. > As the number of simultaneous contending threads increases, Wait-Wound > becomes inferior to Wait-Die in terms of elapsed time. > Possibly due to the larger number of held locks of sleeping transactions. > > Update documentation and callers. > > Timings using git://people.freedesktop.org/~thomash/ww_mutex_test > tag patch-18-06-15 > > Each thread runs 100000 batches of lock / unlock 800 ww mutexes randomly > chosen out of 100000. Four core Intel x86_64: > > Algorithm #threads Rollbacks time > Wound-Wait 4 ~100 ~17s. > Wait-Die 4 ~150000 ~19s. > Wound-Wait 16 ~360000 ~109s. > Wait-Die 16 ~450000 ~82s. > > Cc: Ingo Molnar <mi...@redhat.com> > Cc: Jonathan Corbet <cor...@lwn.net> > Cc: Gustavo Padovan <gust...@padovan.org> > Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com> > Cc: Sean Paul <seanp...@chromium.org> > Cc: David Airlie <airl...@linux.ie> > Cc: Davidlohr Bueso <d...@stgolabs.net> > Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> > Cc: Josh Triplett <j...@joshtriplett.org> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Kate Stewart <kstew...@linuxfoundation.org> > Cc: Philippe Ombredanne <pombreda...@nexb.com> > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > Cc: linux-...@vger.kernel.org > Cc: linux-me...@vger.kernel.org > Cc: linaro-mm-...@lists.linaro.org > Co-authored-by: Peter Zijlstra <pet...@infradead.org> > Signed-off-by: Thomas Hellstrom <thellst...@vmware.com> > > --- > Documentation/locking/ww-mutex-design.txt | 57 +++++++++-- > drivers/dma-buf/reservation.c | 2 +- > drivers/gpu/drm/drm_modeset_lock.c | 2 +- > include/linux/ww_mutex.h | 17 ++- > kernel/locking/locktorture.c | 2 +- > kernel/locking/mutex.c | 165 > +++++++++++++++++++++++++++--- > kernel/locking/test-ww_mutex.c | 2 +- > lib/locking-selftest.c | 2 +- > 8 files changed, 213 insertions(+), 36 deletions(-)
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org> _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
