From: Waiman Long <longman@redhat.com>
To: Ben Gardon <bgardon@google.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Peter Shier <pshier@google.com>,
Peter Feiner <pfeiner@google.com>,
Junaid Shahid <junaids@google.com>,
Jim Mattson <jmattson@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Davidlohr Bueso <dbueso@suse.de>
Subject: Re: [PATCH v2 06/28] locking/rwlocks: Add contention detection for rwlocks
Date: Tue, 9 Feb 2021 22:32:28 -0500 [thread overview]
Message-ID: <6287ff89-d869-e5ed-3e64-11621cc4796a@redhat.com> (raw)
In-Reply-To: <20210202185734.1680553-7-bgardon@google.com>
On 2/2/21 1:57 PM, Ben Gardon wrote:
> rwlocks do not currently have any facility to detect contention
> like spinlocks do. In order to allow users of rwlocks to better manage
> latency, add contention detection for queued rwlocks.
>
> CC: Ingo Molnar <mingo@redhat.com>
> CC: Will Deacon <will@kernel.org>
> Acked-by: Peter Zijlstra <peterz@infradead.org>
> Acked-by: Davidlohr Bueso <dbueso@suse.de>
> Acked-by: Waiman Long <longman@redhat.com>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Ben Gardon <bgardon@google.com>
> ---
> include/asm-generic/qrwlock.h | 24 ++++++++++++++++++------
> include/linux/rwlock.h | 7 +++++++
> 2 files changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
> index 84ce841ce735..0020d3b820a7 100644
> --- a/include/asm-generic/qrwlock.h
> +++ b/include/asm-generic/qrwlock.h
> @@ -14,6 +14,7 @@
> #include <asm/processor.h>
>
> #include <asm-generic/qrwlock_types.h>
> +#include <asm-generic/qspinlock.h>
As said in another thread, qspinlock and qrwlock can be independently
enabled for an architecture. So we shouldn't include qspinlock.h here.
Instead, just include the regular linux/spinlock.h file to make sure
that arch_spin_is_locked() is available.
>
> /*
> * Writer states & reader shift and bias.
> @@ -116,15 +117,26 @@ static inline void queued_write_unlock(struct qrwlock *lock)
> smp_store_release(&lock->wlocked, 0);
> }
>
> +/**
> + * queued_rwlock_is_contended - check if the lock is contended
> + * @lock : Pointer to queue rwlock structure
> + * Return: 1 if lock contended, 0 otherwise
> + */
> +static inline int queued_rwlock_is_contended(struct qrwlock *lock)
> +{
> + return arch_spin_is_locked(&lock->wait_lock);
> +}
> +
> /*
> * Remapping rwlock architecture specific functions to the corresponding
> * queue rwlock functions.
> */
> -#define arch_read_lock(l) queued_read_lock(l)
> -#define arch_write_lock(l) queued_write_lock(l)
> -#define arch_read_trylock(l) queued_read_trylock(l)
> -#define arch_write_trylock(l) queued_write_trylock(l)
> -#define arch_read_unlock(l) queued_read_unlock(l)
> -#define arch_write_unlock(l) queued_write_unlock(l)
> +#define arch_read_lock(l) queued_read_lock(l)
> +#define arch_write_lock(l) queued_write_lock(l)
> +#define arch_read_trylock(l) queued_read_trylock(l)
> +#define arch_write_trylock(l) queued_write_trylock(l)
> +#define arch_read_unlock(l) queued_read_unlock(l)
> +#define arch_write_unlock(l) queued_write_unlock(l)
> +#define arch_rwlock_is_contended(l) queued_rwlock_is_contended(l)
>
> #endif /* __ASM_GENERIC_QRWLOCK_H */
> diff --git a/include/linux/rwlock.h b/include/linux/rwlock.h
> index 3dcd617e65ae..7ce9a51ae5c0 100644
> --- a/include/linux/rwlock.h
> +++ b/include/linux/rwlock.h
> @@ -128,4 +128,11 @@ do { \
> 1 : ({ local_irq_restore(flags); 0; }); \
> })
>
> +#ifdef arch_rwlock_is_contended
> +#define rwlock_is_contended(lock) \
> + arch_rwlock_is_contended(&(lock)->raw_lock)
> +#else
> +#define rwlock_is_contended(lock) ((void)(lock), 0)
> +#endif /* arch_rwlock_is_contended */
> +
> #endif /* __LINUX_RWLOCK_H */
Cheers,
Longman
next prev parent reply other threads:[~2021-02-10 3:34 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 18:57 [PATCH v2 00/28] Allow parallel MMU operations with TDP MMU Ben Gardon
2021-02-02 18:57 ` [PATCH v2 01/28] KVM: x86/mmu: change TDP MMU yield function returns to match cond_resched Ben Gardon
2021-02-02 18:57 ` [PATCH v2 02/28] KVM: x86/mmu: Add comment on __tdp_mmu_set_spte Ben Gardon
2021-02-02 18:57 ` [PATCH v2 03/28] KVM: x86/mmu: Add lockdep when setting a TDP MMU SPTE Ben Gardon
2021-02-02 18:57 ` [PATCH v2 04/28] KVM: x86/mmu: Don't redundantly clear TDP MMU pt memory Ben Gardon
2021-02-02 18:57 ` [PATCH v2 05/28] KVM: x86/mmu: Factor out handling of removed page tables Ben Gardon
2021-02-02 18:57 ` [PATCH v2 06/28] locking/rwlocks: Add contention detection for rwlocks Ben Gardon
2021-02-09 20:39 ` Guenter Roeck
2021-02-09 21:46 ` Waiman Long
2021-02-09 22:25 ` Guenter Roeck
2021-02-10 0:27 ` Waiman Long
2021-02-10 0:41 ` Waiman Long
2021-02-10 6:04 ` Guenter Roeck
2021-02-10 14:57 ` Waiman Long
2021-02-10 3:32 ` Waiman Long [this message]
2021-02-10 15:15 ` Waiman Long
2021-02-02 18:57 ` [PATCH v2 07/28] sched: Add needbreak " Ben Gardon
2021-02-02 18:57 ` [PATCH v2 08/28] sched: Add cond_resched_rwlock Ben Gardon
2021-02-02 18:57 ` [PATCH v2 09/28] KVM: x86/mmu: Fix braces in kvm_recover_nx_lpages Ben Gardon
2021-02-02 18:57 ` [PATCH v2 10/28] KVM: x86/mmu: Fix TDP MMU zap collapsible SPTEs Ben Gardon
2021-02-03 9:43 ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 11/28] KVM: x86/mmu: Merge flush and non-flush tdp_mmu_iter_cond_resched Ben Gardon
2021-02-02 18:57 ` [PATCH v2 12/28] KVM: x86/mmu: Rename goal_gfn to next_last_level_gfn Ben Gardon
2021-02-02 18:57 ` [PATCH v2 13/28] KVM: x86/mmu: Ensure forward progress when yielding in TDP MMU iter Ben Gardon
2021-02-05 23:42 ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 14/28] KVM: x86/mmu: Yield in TDU MMU iter even if no SPTES changed Ben Gardon
2021-02-02 18:57 ` [PATCH v2 15/28] KVM: x86/mmu: Skip no-op changes in TDP MMU functions Ben Gardon
2021-02-02 18:57 ` [PATCH v2 16/28] KVM: x86/mmu: Clear dirtied pages mask bit before early break Ben Gardon
2021-02-02 18:57 ` [PATCH v2 17/28] KVM: x86/mmu: Protect TDP MMU page table memory with RCU Ben Gardon
2021-02-02 18:57 ` [PATCH v2 18/28] KVM: x86/mmu: Use an rwlock for the x86 MMU Ben Gardon
2021-02-02 18:57 ` [PATCH v2 19/28] KVM: x86/mmu: Factor out functions to add/remove TDP MMU pages Ben Gardon
2021-02-02 18:57 ` [PATCH v2 20/28] KVM: x86/mmu: Use atomic ops to set SPTEs in TDP MMU map Ben Gardon
2021-02-03 2:48 ` kernel test robot
2021-02-03 11:14 ` Paolo Bonzini
2021-02-06 0:26 ` Sean Christopherson
2021-02-08 10:32 ` Paolo Bonzini
2021-04-01 10:32 ` Paolo Bonzini
2021-04-01 16:50 ` Ben Gardon
2021-04-01 17:32 ` Paolo Bonzini
2021-04-01 18:09 ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 21/28] KVM: x86/mmu: Flush TLBs after zap in TDP MMU PF handler Ben Gardon
2021-02-06 0:29 ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 22/28] KVM: x86/mmu: Mark SPTEs in disconnected pages as removed Ben Gardon
2021-02-03 11:17 ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 23/28] KVM: x86/mmu: Allow parallel page faults for the TDP MMU Ben Gardon
2021-02-03 12:39 ` Paolo Bonzini
2021-02-03 17:46 ` Ben Gardon
2021-02-03 18:30 ` Paolo Bonzini
2021-02-06 0:12 ` Sean Christopherson
2021-02-02 18:57 ` [PATCH v2 24/28] KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock Ben Gardon
2021-02-03 11:25 ` Paolo Bonzini
2021-02-03 11:26 ` Paolo Bonzini
2021-02-03 18:31 ` Ben Gardon
2021-02-03 18:32 ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 25/28] KVM: x86/mmu: Allow zapping collapsible SPTEs to use MMU " Ben Gardon
2021-02-03 11:34 ` Paolo Bonzini
2021-02-03 18:51 ` Ben Gardon
2021-02-02 18:57 ` [PATCH v2 26/28] KVM: x86/mmu: Allow enabling / disabling dirty logging under " Ben Gardon
2021-02-03 11:38 ` Paolo Bonzini
2021-02-02 18:57 ` [PATCH v2 27/28] KVM: selftests: Add backing src parameter to dirty_log_perf_test Ben Gardon
2021-02-02 18:57 ` [PATCH v2 28/28] KVM: selftests: Disable dirty logging with vCPUs running Ben Gardon
2021-02-03 10:07 ` Paolo Bonzini
2021-02-03 11:00 ` [PATCH v2 00/28] Allow parallel MMU operations with TDP MMU Paolo Bonzini
2021-02-03 17:54 ` Sean Christopherson
2021-02-03 18:13 ` Paolo Bonzini
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