This series replaces the existing paravirtualized spinlock mechanism
with a paravirtualized ticketlock mechanism. The series provides
implementation for both Xen and KVM.
Changes in V9:
- Changed spin_threshold to 32k to avoid excess halt exits that are
causing undercommit degradation (after
This series replaces the existing paravirtualized spinlock mechanism
with a paravirtualized ticketlock mechanism. The series provides
implementation for both Xen and KVM.
Changes in V9:
- Changed spin_threshold to 32k to avoid excess halt exits that are
causing undercommit degradation (after
x86/spinlock: Replace pv spinlocks with pv ticketlocks
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Rather than outright replacing the entire spinlock implementation in
order to paravirtualize it, keep the ticket lock implementation but add
a couple of pvops hooks on the slow patch
x86/ticketlock: Don't inline _spin_unlock when using paravirt spinlocks
From: Raghavendra K T raghavendra...@linux.vnet.ibm.com
The code size expands somewhat, and its better to just call
a function rather than inline it.
Thanks Jeremy for original version of ARCH_NOINLINE_SPIN_UNLOCK config
x86/ticketlock: Collapse a layer of functions
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Now that the paravirtualization layer doesn't exist at the spinlock
level any more, we can collapse the __ticket_ functions into the arch_
functions.
Signed-off-by: Jeremy Fitzhardinge
xen: Defer spinlock setup until boot CPU setup
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
There's no need to do it at very early init, and doing it there
makes it impossible to use the jump_label machinery.
Signed-off-by: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
xen/pvticketlock: Xen implementation for PV ticket locks
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Replace the old Xen implementation of PV spinlocks with and implementation
of xen_lock_spinning and xen_unlock_kick.
xen_lock_spinning simply registers the cpu in its entry in
Split jumplabel ratelimit
From: Andrew Jones drjo...@redhat.com
Commit b202952075f62603bea9bfb6ebc6b0420db11949 introduced rate limiting
for jump label disabling. The changes were made in the jump label code
in order to be more widely available and to keep things tidier. This is
all fine, except
x86/pvticketlock: Use callee-save for lock_spinning
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Although the lock_spinning calls in the spinlock code are on the
uncommon path, their presence can cause the compiler to generate many
more register save/restores in the function
x86/pvticketlock: When paravirtualizing ticket locks, increment by 2
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Increment ticket head/tails by 2 rather than 1 to leave the LSB free
to store a is in slowpath state bit. This halves the number
of possible CPUs for a given ticket
xen/pvticketlocks: Add xen_nopvspin parameter to disable xen pv ticketlocks
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Signed-off-by: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Reviewed-by: Konrad Rzeszutek Wilk konrad.w...@oracle.com
Signed-off-by: Raghavendra K T
xen/pvticketlock: Allow interrupts to be enabled while blocking
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
If interrupts were enabled when taking the spinlock, we can leave them
enabled while blocking to get the lock.
If we can enable interrupts while waiting for the lock to
kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor
From: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
During smp_boot_cpus paravirtualied KVM guest detects if the hypervisor has
required feature (KVM_FEATURE_PV_UNHALT) to support pv-ticketlocks. If so,
support for
xen: Enable PV ticketlocks on HVM Xen
From: Stefano Stabellini stefano.stabell...@eu.citrix.com
Signed-off-by: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Reviewed-by: Konrad Rzeszutek Wilk konrad.w...@oracle.com
Signed-off-by: Raghavendra K T raghavendra...@linux.vnet.ibm.com
---
kvm : Fold pv_unhalt flag into GET_MP_STATE ioctl to aid migration
From: Raghavendra K T raghavendra...@linux.vnet.ibm.com
During migration, any vcpu that got kicked but did not become runnable
(still in halted state) should be runnable after migration.
Signed-off-by: Raghavendra K T
kvm guest : Add configuration support to enable debug information for KVM Guests
From: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
Signed-off-by: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
Signed-off-by: Suzuki Poulose suz...@in.ibm.com
Signed-off-by: Raghavendra K T
Simplify kvm_for_each_vcpu with kvm_irq_delivery_to_apic
From: Raghavendra K T raghavendra...@linux.vnet.ibm.com
Note that we are using APIC_DM_REMRD which has reserved usage.
In future if APIC_DM_REMRD usage is standardized, then we should
find some other way or go back to old method.
Documentation/kvm : Add documentation on Hypercalls and features used for PV
spinlock
From: Raghavendra K T raghavendra...@linux.vnet.ibm.com
KVM_HC_KICK_CPU hypercall added to wakeup halted vcpu in paravirtual spinlock
enabled guest.
KVM_FEATURE_PV_UNHALT enables guest to check whether pv
kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks
From: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
kvm_hc_kick_cpu allows the calling vcpu to kick another vcpu out of halt state.
the presence of these hypercalls is indicated to guest via
kvm_feature_pv_unhalt.
kvm hypervisor: Add directed yield in vcpu block path
From: Raghavendra K T raghavendra...@linux.vnet.ibm.com
We use the improved PLE handler logic in vcpu block patch for
scheduling rather than plain schedule, so that we can make
intelligent decisions
Signed-off-by: Raghavendra K T
x86/ticketlock: Add slowpath logic
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
Maintain a flag in the LSB of the ticket lock tail which indicates
whether anyone is in the lock slowpath and may need kicking when
the current holder unlocks. The flags are set when the first locker
FWIW I use the paravirt spinlock ops for adding lock elision
to the spinlocks.
This needs to be done at the top level (so the level you're removing)
However I don't like the pv mechanism very much and would
be fine with using an static key hook in the main path
like I do for all the other lock
On 06/01/2013 01:14 PM, Andi Kleen wrote:
FWIW I use the paravirt spinlock ops for adding lock elision
to the spinlocks.
Does lock elision still use the ticketlock algorithm/structure, or are
they different? If they're still basically ticketlocks, then it seems
to me that they're complimentary
On 06/01/2013 12:21 PM, Raghavendra K T wrote:
x86/spinlock: Replace pv spinlocks with pv ticketlocks
From: Jeremy Fitzhardinge jeremy.fitzhardi...@citrix.com
I'm not sure what the etiquette is here; I did the work while at Citrix,
but jer...@goop.org is my canonical email address. The Citrix
On Sat, Jun 01, 2013 at 01:28:00PM -0700, Jeremy Fitzhardinge wrote:
On 06/01/2013 01:14 PM, Andi Kleen wrote:
FWIW I use the paravirt spinlock ops for adding lock elision
to the spinlocks.
Does lock elision still use the ticketlock algorithm/structure, or are
they different? If they're
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