similar to: [PATCH v12 00/11] qspinlock: a 4-byte queue spinlock with PV support

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

v10->v11: - Use a simple test-and-set unfair lock to simplify the code, but performance may suffer a bit for large guest with many CPUs. - Take out Raghavendra KT's test results as the unfair lock changes may render some of his results invalid. - Add PV support without increasing the size of the core queue node structure. - Other minor changes to address some of the

v10->v11: - Use a simple test-and-set unfair lock to simplify the code, but performance may suffer a bit for large guest with many CPUs. - Take out Raghavendra KT's test results as the unfair lock changes may render some of his results invalid. - Add PV support without increasing the size of the core queue node structure. - Other minor changes to address some of the

v9->v10: - Make some minor changes to qspinlock.c to accommodate review feedback. - Change author to PeterZ for 2 of the patches. - Include Raghavendra KT's test results in patch 18. v8->v9: - Integrate PeterZ's version of the queue spinlock patch with some modification: http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org - Break the more complex

v9->v10: - Make some minor changes to qspinlock.c to accommodate review feedback. - Change author to PeterZ for 2 of the patches. - Include Raghavendra KT's test results in patch 18. v8->v9: - Integrate PeterZ's version of the queue spinlock patch with some modification: http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org - Break the more complex

v8->v9: - Integrate PeterZ's version of the queue spinlock patch with some modification: http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org - Break the more complex patches into smaller ones to ease review effort. - Fix a racing condition in the PV qspinlock code. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving

v8->v9: - Integrate PeterZ's version of the queue spinlock patch with some modification: http://lkml.kernel.org/r/20140310154236.038181843 at infradead.org - Break the more complex patches into smaller ones to ease review effort. - Fix a racing condition in the PV qspinlock code. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving

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

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

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

v15->v16: - Remove the lfsr patch and use linear probing as lfsr is not really necessary in most cases. - Move the paravirt PV_CALLEE_SAVE_REGS_THUNK code to an asm header. - Add a patch to collect PV qspinlock statistics which also supersedes the PV lock hash debug patch. - Add PV qspinlock performance numbers. v14->v15: - Incorporate PeterZ's v15 qspinlock patch and improve

v15->v16: - Remove the lfsr patch and use linear probing as lfsr is not really necessary in most cases. - Move the paravirt PV_CALLEE_SAVE_REGS_THUNK code to an asm header. - Add a patch to collect PV qspinlock statistics which also supersedes the PV lock hash debug patch. - Add PV qspinlock performance numbers. v14->v15: - Incorporate PeterZ's v15 qspinlock patch and improve

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.

v5->v6: - Change the optimized 2-task contending code to make it fairer at the expense of a bit of performance. - Add a patch to support unfair queue spinlock for Xen. - Modify the PV qspinlock code to follow what was done in the PV ticketlock. - Add performance data for the unfair lock as well as the PV support code. v4->v5: - Move the optimized 2-task contending code to the

v5->v6: - Change the optimized 2-task contending code to make it fairer at the expense of a bit of performance. - Add a patch to support unfair queue spinlock for Xen. - Modify the PV qspinlock code to follow what was done in the PV ticketlock. - Add performance data for the unfair lock as well as the PV support code. v4->v5: - Move the optimized 2-task contending code to the