search for: qnode

In order to support additional virtualization features like unfair lock and para-virtualized spinlock, it is necessary to store additional CPU specific data into the queue node structure. As a result, a new qnode structure is created and the mcs_spinlock structure is now part of the new structure. It is also necessary to expand arch_mcs_spin_lock_contended() to the underlying while loop as additional code will need to be inserted into the loop. Signed-off-by: Waiman Long <Waiman.Long at hp.com> ---...

...147 +++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 146 insertions(+), 1 deletions(-) diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c index a14241e..06dd486 100644 --- a/kernel/locking/qspinlock.c +++ b/kernel/locking/qspinlock.c @@ -63,6 +63,11 @@ */ struct qnode { struct mcs_spinlock mcs; +#ifdef CONFIG_PARAVIRT_UNFAIR_LOCKS + int lsteal_mask; /* Lock stealing frequency mask */ + u32 prev_tail; /* Tail code of previous node */ + struct qnode *qprev; /* Previous queue node addr */ +#endif }; #define qhead mcs.locked /* The queue head flag */ @@ -...

On Wed, Feb 26, 2014 at 10:14:21AM -0500, Waiman Long wrote: > +struct qnode { > + u32 wait; /* Waiting flag */ > + struct qnode *next; /* Next queue node addr */ > +}; > + > +struct qnode_set { > + struct qnode nodes[MAX_QNODES]; > + int node_idx; /* Current node to use */ > +}; > + > +/* > + * Per-CPU queue node structures > + */...

...t 11:01:36AM -0400, Waiman Long wrote: > /* > + * To have additional features for better virtualization support, it is > + * necessary to store additional data in the queue node structure. So > + * a new queue node structure will have to be defined and used here. > + */ > +struct qnode { > + struct mcs_spinlock mcs; > +}; You can ditch this entire patch; its pointless, just add a new DEFINE_PER_CPU for the para-virt muck.

On Wed, Feb 26, 2014 at 10:14:21AM -0500, Waiman Long wrote: > +struct qnode { > + u32 wait; /* Waiting flag */ > + struct qnode *next; /* Next queue node addr */ > +}; > + > +struct qnode_set { > + struct qnode nodes[MAX_QNODES]; > + int node_idx; /* Current node to use */ > +}; > + > +/* > + * Per-CPU queue node structures > + */...

...t 11:01:36AM -0400, Waiman Long wrote: > /* > + * To have additional features for better virtualization support, it is > + * necessary to store additional data in the queue node structure. So > + * a new queue node structure will have to be defined and used here. > + */ > +struct qnode { > + struct mcs_spinlock mcs; > +}; You can ditch this entire patch; its pointless, just add a new DEFINE_PER_CPU for the para-virt muck.

...gt; /* > >>+ * To have additional features for better virtualization support, it is > >>+ * necessary to store additional data in the queue node structure. So > >>+ * a new queue node structure will have to be defined and used here. > >>+ */ > >>+struct qnode { > >>+ struct mcs_spinlock mcs; > >>+}; > >You can ditch this entire patch; its pointless, just add a new > >DEFINE_PER_CPU for the para-virt muck. > > Yes, I can certainly merge it to the next one in the series. I break it out > to make each individual patc...

...gt; /* > >>+ * To have additional features for better virtualization support, it is > >>+ * necessary to store additional data in the queue node structure. So > >>+ * a new queue node structure will have to be defined and used here. > >>+ */ > >>+struct qnode { > >>+ struct mcs_spinlock mcs; > >>+}; > >You can ditch this entire patch; its pointless, just add a new > >DEFINE_PER_CPU for the para-virt muck. > > Yes, I can certainly merge it to the next one in the series. I break it out > to make each individual patc...

...n Long wrote: >> /* >> + * To have additional features for better virtualization support, it is >> + * necessary to store additional data in the queue node structure. So >> + * a new queue node structure will have to be defined and used here. >> + */ >> +struct qnode { >> + struct mcs_spinlock mcs; >> +}; > You can ditch this entire patch; its pointless, just add a new > DEFINE_PER_CPU for the para-virt muck. Yes, I can certainly merge it to the next one in the series. I break it out to make each individual patch smaller, more single-purpose...

...* + * CPU state flags + */ +#define PV_CPU_ACTIVE 1 /* This CPU is active */ +#define PV_CPU_KICKING 2 /* This CPU is kicking other CPU */ +#define PV_CPU_KICKED 3 /* This CPU is being kicked */ +#define PV_CPU_HALTED -1 /* This CPU is halted */ + +/* + * Additional fields to be added to the qnode structure + */ +#if CONFIG_NR_CPUS >= (1 << 16) +#define _cpuid_t u32 +#else +#define _cpuid_t u16 +#endif + +struct qnode; + +struct pv_qvars { + s16 cpustate; /* CPU status flag */ + _cpuid_t nxtcpu_p1; /* CPU number of next node + 1 */ + _cpuid_t mycpu; /* CPU number...

...e x86-64 to use queue spinlock qspinlock: Add pending bit qspinlock: Extract out the exchange of tail code word qspinlock: Optimize for smaller NR_CPUS qspinlock: prolong the stay in the pending bit path qspinlock: Use a simple write to grab the lock, if applicable qspinlock: Make a new qnode structure to support virtualization qspinlock: Prepare for unfair lock support qspinlock, x86: Allow unfair spinlock in a virtual guest qspinlock: Split the MCS queuing code into a separate slowerpath unfair qspinlock: Variable frequency lock stealing mechanism unfair qspinlock: Enable lo...

...e x86-64 to use queue spinlock qspinlock: Add pending bit qspinlock: Extract out the exchange of tail code word qspinlock: Optimize for smaller NR_CPUS qspinlock: prolong the stay in the pending bit path qspinlock: Use a simple write to grab the lock, if applicable qspinlock: Make a new qnode structure to support virtualization qspinlock: Prepare for unfair lock support qspinlock, x86: Allow unfair spinlock in a virtual guest qspinlock: Split the MCS queuing code into a separate slowerpath unfair qspinlock: Variable frequency lock stealing mechanism unfair qspinlock: Enable lo...

...* Threahold for clearing active flag */ +#define CLEAR_ACTIVE_MASK (CLEAR_ACTIVE_THRESHOLD - 1) + +/* + * PV macros + */ +#define PV_SET_VAR(type, var, val) type var = val +#define PV_VAR(var) var +#define PV_GET_NXTCPU(node) (node)->pv.nxtcpu_p1 + +/* + * Additional fields to be added to the qnode structure + * + * Try to cram the PV fields into a 32 bits so that it won't increase the + * qnode size in x86-64. + */ +#if CONFIG_NR_CPUS >= (1 << 16) +#define _cpuid_t u32 +#else +#define _cpuid_t u16 +#endif + +struct pv_qvars { + u8 active; /* Set if CPU active */ + u8 prehead;...

...pinlock: A simple generic 4-byte queue spinlock qspinlock, x86: Enable x86-64 to use queue spinlock qspinlock: Extract out the exchange of tail code word qspinlock: prolong the stay in the pending bit path qspinlock: Use a simple write to grab the lock, if applicable qspinlock: Make a new qnode structure to support virtualization qspinlock: Prepare for unfair lock support qspinlock, x86: Allow unfair spinlock in a virtual guest qspinlock: Split the MCS queuing code into a separate slowerpath unfair qspinlock: Variable frequency lock stealing mechanism unfair qspinlock: Enable lo...

...pinlock: A simple generic 4-byte queue spinlock qspinlock, x86: Enable x86-64 to use queue spinlock qspinlock: Extract out the exchange of tail code word qspinlock: prolong the stay in the pending bit path qspinlock: Use a simple write to grab the lock, if applicable qspinlock: Make a new qnode structure to support virtualization qspinlock: Prepare for unfair lock support qspinlock, x86: Allow unfair spinlock in a virtual guest qspinlock: Split the MCS queuing code into a separate slowerpath unfair qspinlock: Variable frequency lock stealing mechanism unfair qspinlock: Enable lo...

v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit to enable/disable unfair lock. - Reduce unfair lock slowpath lock stealing frequency depending on its distance from the queue head. - Add performance data for IvyBridge-EX CPU.

v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit to enable/disable unfair lock. - Reduce unfair lock slowpath lock stealing frequency depending on its distance from the queue head. - Add performance data for IvyBridge-EX CPU.

N.B. Sorry for the duplicate. This patch series were resent as the original one was rejected by the vger.kernel.org list server due to long header. There is no change in content. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit

N.B. Sorry for the duplicate. This patch series were resent as the original one was rejected by the vger.kernel.org list server due to long header. There is no change in content. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit

v6->v7: - Remove an atomic operation from the 2-task contending code - Shorten the names of some macros - Make the queue waiter to attempt to steal lock when unfair lock is enabled. - Remove lock holder kick from the PV code and fix a race condition - Run the unfair lock & PV code on overcommitted KVM guests to collect performance data. v5->v6: - Change the optimized