similar to: [PATCH v16 00/14] qspinlock: a 4-byte queue spinlock with PV support

v14->v15: - Incorporate PeterZ's v15 qspinlock patch and improve upon the PV qspinlock code by dynamically allocating the hash table as well as some other performance optimization. - Simplified the Xen PV qspinlock code as suggested by David Vrabel <david.vrabel at citrix.com>. - Add benchmarking data for 3.19 kernel to compare the performance of a spinlock heavy test

v14->v15: - Incorporate PeterZ's v15 qspinlock patch and improve upon the PV qspinlock code by dynamically allocating the hash table as well as some other performance optimization. - Simplified the Xen PV qspinlock code as suggested by David Vrabel <david.vrabel at citrix.com>. - Add benchmarking data for 3.19 kernel to compare the performance of a spinlock heavy test

Hi Waiman, As promised; here is the paravirt stuff I did during the trip to BOS last week. All the !paravirt patches are more or less the same as before (the only real change is the copyright lines in the first patch). The paravirt stuff is 'simple' and KVM only -- the Xen code was a little more convoluted and I've no real way to test that but it should be stright fwd to make work.

Hi Waiman, As promised; here is the paravirt stuff I did during the trip to BOS last week. All the !paravirt patches are more or less the same as before (the only real change is the copyright lines in the first patch). The paravirt stuff is 'simple' and KVM only -- the Xen code was a little more convoluted and I've no real way to test that but it should be stright fwd to make work.

On 03/16/2015 09:16 AM, Peter Zijlstra wrote: > Implement simple paravirt support for the qspinlock. > > Provide a separate (second) version of the spin_lock_slowpath for > paravirt along with a special unlock path. > > The second slowpath is generated by adding a few pv hooks to the > normal slowpath, but where those will compile away for the native > case, they expand

On 03/16/2015 09:16 AM, Peter Zijlstra wrote: > Implement simple paravirt support for the qspinlock. > > Provide a separate (second) version of the spin_lock_slowpath for > paravirt along with a special unlock path. > > The second slowpath is generated by adding a few pv hooks to the > normal slowpath, but where those will compile away for the native > case, they expand

On Mon, Apr 06, 2015 at 10:55:44PM -0400, Waiman Long wrote: > +++ b/kernel/locking/qspinlock_paravirt.h > @@ -0,0 +1,321 @@ > +#ifndef _GEN_PV_LOCK_SLOWPATH > +#error "do not include this file" > +#endif > + > +/* > + * Implement paravirt qspinlocks; the general idea is to halt the vcpus instead > + * of spinning them. > + * > + * This relies on the

On Mon, Apr 06, 2015 at 10:55:44PM -0400, Waiman Long wrote: > +++ b/kernel/locking/qspinlock_paravirt.h > @@ -0,0 +1,321 @@ > +#ifndef _GEN_PV_LOCK_SLOWPATH > +#error "do not include this file" > +#endif > + > +/* > + * Implement paravirt qspinlocks; the general idea is to halt the vcpus instead > + * of spinning them. > + * > + * This relies on the

On Mon, Apr 06, 2015 at 10:55:48PM -0400, Waiman Long wrote: > @@ -219,24 +236,30 @@ static void pv_wait_node(struct mcs_spinlock *node) > } > > /* > + * Called after setting next->locked = 1 & lock acquired. > + * Check if the the CPU has been halted. If so, set the _Q_SLOW_VAL flag > + * and put an entry into the lock hash table to be waken up at unlock time.

On Mon, Apr 06, 2015 at 10:55:48PM -0400, Waiman Long wrote: > @@ -219,24 +236,30 @@ static void pv_wait_node(struct mcs_spinlock *node) > } > > /* > + * Called after setting next->locked = 1 & lock acquired. > + * Check if the the CPU has been halted. If so, set the _Q_SLOW_VAL flag > + * and put an entry into the lock hash table to be waken up at unlock time.

Since Waiman seems incapable of doing simple things; here's my take on the paravirt crap. The first few patches are taken from Waiman's latest series, but the virt support is completely new. Its primary aim is to not mess up the native code. I've not stress tested it, but the virt and paravirt (kvm) cases boot on simple smp guests. I've not done Xen, but the patch should be

Since Waiman seems incapable of doing simple things; here's my take on the paravirt crap. The first few patches are taken from Waiman's latest series, but the virt support is completely new. Its primary aim is to not mess up the native code. I've not stress tested it, but the virt and paravirt (kvm) cases boot on simple smp guests. I've not done Xen, but the patch should be

On Thu, Apr 09, 2015 at 05:41:44PM -0400, Waiman Long wrote: > >>+static void pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) > >>+{ > >>+ struct __qspinlock *l = (void *)lock; > >>+ struct qspinlock **lp = NULL; > >>+ struct pv_node *pn = (struct pv_node *)node; > >>+ int slow_set = false; > >>+ int loop; >

On Thu, Apr 09, 2015 at 05:41:44PM -0400, Waiman Long wrote: > >>+static void pv_wait_head(struct qspinlock *lock, struct mcs_spinlock *node) > >>+{ > >>+ struct __qspinlock *l = (void *)lock; > >>+ struct qspinlock **lp = NULL; > >>+ struct pv_node *pn = (struct pv_node *)node; > >>+ int slow_set = false; > >>+ int loop; >

v13->v14: - Patches 1 & 2: Add queue_spin_unlock_wait() to accommodate commit 78bff1c86 from Oleg Nesterov. - Fix the system hang problem when using PV qspinlock in an over-committed guest due to a racing condition in the pv_set_head_in_tail() function. - Increase the MAYHALT_THRESHOLD from 10 to 1024. - Change kick_cpu into a regular function pointer instead of a

v13->v14: - Patches 1 & 2: Add queue_spin_unlock_wait() to accommodate commit 78bff1c86 from Oleg Nesterov. - Fix the system hang problem when using PV qspinlock in an over-committed guest due to a racing condition in the pv_set_head_in_tail() function. - Increase the MAYHALT_THRESHOLD from 10 to 1024. - Change kick_cpu into a regular function pointer instead of a

v12->v13: - Change patch 9 to generate separate versions of the queue_spin_lock_slowpath functions for bare metal and PV guest. This reduces the performance impact of the PV code on bare metal systems. v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo

v12->v13: - Change patch 9 to generate separate versions of the queue_spin_lock_slowpath functions for bare metal and PV guest. This reduces the performance impact of the PV code on bare metal systems. v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo

v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo Bonzini. - The pvqspinlock code is largely from my previous version with PeterZ's way of going from queue tail to head and his idea of using callee saved calls to KVM and XEN codes. v10->v11: - Use a

v11->v12: - Based on PeterZ's version of the qspinlock patch (https://lkml.org/lkml/2014/6/15/63). - Incorporated many of the review comments from Konrad Wilk and Paolo Bonzini. - The pvqspinlock code is largely from my previous version with PeterZ's way of going from queue tail to head and his idea of using callee saved calls to KVM and XEN codes. v10->v11: - Use a