From: Ben Gardon <bgardon@google.com>
To: 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>,
Ben Gardon <bgardon@google.com>, Ingo Molnar <mingo@redhat.com>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Davidlohr Bueso <dbueso@suse.de>,
Waiman Long <longman@redhat.com>
Subject: [PATCH v2 07/28] sched: Add needbreak for rwlocks
Date: Tue, 2 Feb 2021 10:57:13 -0800 [thread overview]
Message-ID: <20210202185734.1680553-8-bgardon@google.com> (raw)
In-Reply-To: <20210202185734.1680553-1-bgardon@google.com>
Contention awareness while holding a spin lock is essential for reducing
latency when long running kernel operations can hold that lock. Add the
same contention detection interface for read/write spin locks.
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/linux/sched.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6e3a5eeec509..5d1378e5a040 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1912,6 +1912,23 @@ static inline int spin_needbreak(spinlock_t *lock)
#endif
}
+/*
+ * Check if a rwlock is contended.
+ * Returns non-zero if there is another task waiting on the rwlock.
+ * Returns zero if the lock is not contended or the system / underlying
+ * rwlock implementation does not support contention detection.
+ * Technically does not depend on CONFIG_PREEMPTION, but a general need
+ * for low latency.
+ */
+static inline int rwlock_needbreak(rwlock_t *lock)
+{
+#ifdef CONFIG_PREEMPTION
+ return rwlock_is_contended(lock);
+#else
+ return 0;
+#endif
+}
+
static __always_inline bool need_resched(void)
{
return unlikely(tif_need_resched());
--
2.30.0.365.g02bc693789-goog
next prev parent reply other threads:[~2021-02-02 19:02 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
2021-02-10 15:15 ` Waiman Long
2021-02-02 18:57 ` Ben Gardon [this message]
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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