search for: xen_nopvspin

On 11/01/2017 04:58 PM, Waiman Long wrote: > +/* TODO: To be removed in a future kernel version */ > static __init int xen_parse_nopvspin(char *arg) > { > - xen_pvspin = false; > + pr_warn("xen_nopvspin is deprecated, replace it with \"pvlock_type=queued\"!\n"); > + if (!pv_spinlock_type) > + pv_spinlock_type = locktype_queued; Since we currently end up using unfair locks and because you are deprecating xen_nopvspin I wonder whether it would be better to set this to locktype...

On 11/01/2017 04:58 PM, Waiman Long wrote: > +/* TODO: To be removed in a future kernel version */ > static __init int xen_parse_nopvspin(char *arg) > { > - xen_pvspin = false; > + pr_warn("xen_nopvspin is deprecated, replace it with \"pvlock_type=queued\"!\n"); > + if (!pv_spinlock_type) > + pv_spinlock_type = locktype_queued; Since we currently end up using unfair locks and because you are deprecating xen_nopvspin I wonder whether it would be better to set this to locktype...

With the new pvlock_type kernel parameter, xen_nopvspin is no longer needed. This patch deprecates the xen_nopvspin parameter by removing its documentation and treating it as an alias of "pvlock_type=queued". Signed-off-by: Waiman Long <longman at redhat.com> --- Documentation/admin-guide/kernel-parameters.txt | 4 ---- arch/x86/xen/s...

...t lock types so that they can come >> up with a better algorithm to pick the best lock type. >> >> The hypervisor paravirt spinlock code will override this new parameter >> in determining if pvqspinlock should be used. The parameter, however, >> will override Xen's xen_nopvspin in term of disabling unfair lock. > Hmm, I'm not sure we need pvlock_type _and_ xen_nopvspin. What do others > think? I don't think we need xen_nopvspin, but I don't want to remove that without agreement from the community. >> DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key); &g...

...t lock types so that they can come >> up with a better algorithm to pick the best lock type. >> >> The hypervisor paravirt spinlock code will override this new parameter >> in determining if pvqspinlock should be used. The parameter, however, >> will override Xen's xen_nopvspin in term of disabling unfair lock. > Hmm, I'm not sure we need pvlock_type _and_ xen_nopvspin. What do others > think? I don't think we need xen_nopvspin, but I don't want to remove that without agreement from the community. >> DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key); &g...

On 11/01/2017 06:01 PM, Boris Ostrovsky wrote: > On 11/01/2017 04:58 PM, Waiman Long wrote: >> +/* TODO: To be removed in a future kernel version */ >> static __init int xen_parse_nopvspin(char *arg) >> { >> - xen_pvspin = false; >> + pr_warn("xen_nopvspin is deprecated, replace it with \"pvlock_type=queued\"!\n"); >> + if (!pv_spinlock_type) >> + pv_spinlock_type = locktype_queued; > Since we currently end up using unfair locks and because you are > deprecating xen_nopvspin I wonder whether it would be better to set...

v1->v2: - Make pv_spinlock_type a bit mask for easier checking. - Add patch 2 to deprecate xen_nopvspin v1 - https://lkml.org/lkml/2017/11/1/381 Patch 1 adds a new pvlock_type parameter for the administrators to specify the type of lock to be used in a para-virtualized kernel. Patch 2 deprecates Xen's xen_nopvspin parameter as it is no longer needed. Waiman Long (2): x86/paravirt: Add kerne...

v1->v2: - Make pv_spinlock_type a bit mask for easier checking. - Add patch 2 to deprecate xen_nopvspin v1 - https://lkml.org/lkml/2017/11/1/381 Patch 1 adds a new pvlock_type parameter for the administrators to specify the type of lock to be used in a para-virtualized kernel. Patch 2 deprecates Xen's xen_nopvspin parameter as it is no longer needed. Waiman Long (2): x86/paravirt: Add kerne...

With the boot parameter "xen_nopvspin" specified a Xen guest should not make use of paravirt spinlocks, but behave as if running on bare metal. This is not true, however, as the qspinlock code will fall back to a test-and-set scheme when it is detecting a hypervisor. In order to avoid this disable the virt_spin_lock_key. Signed-...

...they can come >>> up with a better algorithm to pick the best lock type. >>> >>> The hypervisor paravirt spinlock code will override this new parameter >>> in determining if pvqspinlock should be used. The parameter, however, >>> will override Xen's xen_nopvspin in term of disabling unfair lock. >> Hmm, I'm not sure we need pvlock_type _and_ xen_nopvspin. What do others >> think? > I don't think we need xen_nopvspin, but I don't want to remove that > without agreement from the community. I also don't think xen_nopvspin wi...

.... V3: - remove test for hypervisor environment from virt_spin_lock(9 as suggested by Waiman Long V2: - use static key instead of making virt_spin_lock() a pvops function Juergen Gross (2): paravirt/locks: use new static key for controlling call of virt_spin_lock() paravirt,xen: correct xen_nopvspin case arch/x86/include/asm/qspinlock.h | 11 ++++++++++- arch/x86/kernel/paravirt-spinlocks.c | 6 ++++++ arch/x86/kernel/smpboot.c | 2 ++ arch/x86/xen/spinlock.c | 2 ++ kernel/locking/qspinlock.c | 4 ++++ 5 files changed, 24 insertions(+), 1 deletion(-...

.... V3: - remove test for hypervisor environment from virt_spin_lock(9 as suggested by Waiman Long V2: - use static key instead of making virt_spin_lock() a pvops function Juergen Gross (2): paravirt/locks: use new static key for controlling call of virt_spin_lock() paravirt,xen: correct xen_nopvspin case arch/x86/include/asm/qspinlock.h | 11 ++++++++++- arch/x86/kernel/paravirt-spinlocks.c | 6 ++++++ arch/x86/kernel/smpboot.c | 2 ++ arch/x86/xen/spinlock.c | 2 ++ kernel/locking/qspinlock.c | 4 ++++ 5 files changed, 24 insertions(+), 1 deletion(-...

...locks, the current fallback to the unfair test-and-set scheme, or to mimic the bare metal behavior. V2: - use static key instead of making virt_spin_lock() a pvops function Juergen Gross (2): paravirt/locks: use new static key for controlling call of virt_spin_lock() paravirt,xen: correct xen_nopvspin case arch/x86/include/asm/qspinlock.h | 11 +++++++++++ arch/x86/kernel/paravirt-spinlocks.c | 6 ++++++ arch/x86/kernel/smpboot.c | 2 ++ arch/x86/xen/spinlock.c | 2 ++ kernel/locking/qspinlock.c | 4 ++++ 5 files changed, 25 insertions(+) -- 2.12.3

...locks, the current fallback to the unfair test-and-set scheme, or to mimic the bare metal behavior. V2: - use static key instead of making virt_spin_lock() a pvops function Juergen Gross (2): paravirt/locks: use new static key for controlling call of virt_spin_lock() paravirt,xen: correct xen_nopvspin case arch/x86/include/asm/qspinlock.h | 11 +++++++++++ arch/x86/kernel/paravirt-spinlocks.c | 6 ++++++ arch/x86/kernel/smpboot.c | 2 ++ arch/x86/xen/spinlock.c | 2 ++ kernel/locking/qspinlock.c | 4 ++++ 5 files changed, 25 insertions(+) -- 2.12.3

...an also use that to experiment with different lock types so that they can come up with a better algorithm to pick the best lock type. The hypervisor paravirt spinlock code will override this new parameter in determining if pvqspinlock should be used. The parameter, however, will override Xen's xen_nopvspin in term of disabling unfair lock. Signed-off-by: Waiman Long <longman at redhat.com> --- Documentation/admin-guide/kernel-parameters.txt | 7 +++++ arch/x86/include/asm/paravirt.h | 9 ++++++ arch/x86/kernel/kvm.c | 4 +++ arch/x86/kernel/paravir...

...an also use that to experiment with different lock types so that they can come up with a better algorithm to pick the best lock type. The hypervisor paravirt spinlock code will override this new parameter in determining if pvqspinlock should be used. The parameter, however, will override Xen's xen_nopvspin in term of disabling unfair lock. Signed-off-by: Waiman Long <longman at redhat.com> --- Documentation/admin-guide/kernel-parameters.txt | 7 +++++ arch/x86/include/asm/paravirt.h | 9 ++++++ arch/x86/kernel/kvm.c | 4 +++ arch/x86/kernel/paravir...

...llback to the unfair test-and-set scheme, or to mimic the bare metal behavior. Juergen Gross (4): paravirt: add generic _paravirt_false() function paravirt: switch vcpu_is_preempted to use _paravirt_false() on bare metal paravirt: add virt_spin_lock pvops function paravirt,xen: correct xen_nopvspin case arch/x86/include/asm/paravirt.h | 5 ++++ arch/x86/include/asm/paravirt_types.h | 3 +++ arch/x86/include/asm/qspinlock.h | 48 ++++++++++++++++++++++++----------- arch/x86/kernel/paravirt-spinlocks.c | 22 ++++++++-------- arch/x86/kernel/paravirt.c | 7 +++++ arch...

...llback to the unfair test-and-set scheme, or to mimic the bare metal behavior. Juergen Gross (4): paravirt: add generic _paravirt_false() function paravirt: switch vcpu_is_preempted to use _paravirt_false() on bare metal paravirt: add virt_spin_lock pvops function paravirt,xen: correct xen_nopvspin case arch/x86/include/asm/paravirt.h | 5 ++++ arch/x86/include/asm/paravirt_types.h | 3 +++ arch/x86/include/asm/qspinlock.h | 48 ++++++++++++++++++++++++----------- arch/x86/kernel/paravirt-spinlocks.c | 22 ++++++++-------- arch/x86/kernel/paravirt.c | 7 +++++ arch...

...iment with different lock types so that they can come > up with a better algorithm to pick the best lock type. > > The hypervisor paravirt spinlock code will override this new parameter > in determining if pvqspinlock should be used. The parameter, however, > will override Xen's xen_nopvspin in term of disabling unfair lock. Hmm, I'm not sure we need pvlock_type _and_ xen_nopvspin. What do others think? > > Signed-off-by: Waiman Long <longman at redhat.com> > --- > Documentation/admin-guide/kernel-parameters.txt | 7 +++++ > arch/x86/include/asm/paravirt.h...

On 09/05/2017 10:18 AM, Juergen Gross wrote: > On 05/09/17 16:10, Waiman Long wrote: >> On 09/05/2017 09:24 AM, Juergen Gross wrote: >>> There are cases where a guest tries to switch spinlocks to bare metal >>> behavior (e.g. by setting "xen_nopvspin" boot parameter). Today this >>> has the downside of falling back to unfair test and set scheme for >>> qspinlocks due to virt_spin_lock() detecting the virtualized >>> environment. >>> >>> Make virt_spin_lock() a paravirt operation in order to enab...