From: Sean Christopherson <seanjc@google.com>
To: bugzilla-daemon@kernel.org
Cc: kvm@vger.kernel.org
Subject: Re: [Bug 218259] High latency in KVM guests
Date: Thu, 11 Jan 2024 07:55:03 -0800 [thread overview]
Message-ID: <ZaAPV7cNTRVTmn7g@google.com> (raw)
In-Reply-To: <bug-218259-28872-oOlnHKCFQq@https.bugzilla.kernel.org/>
On Mon, Dec 18, 2023, bugzilla-daemon@kernel.org wrote:
> > I think the kernel is preemptible:
>
> Ya, not fully preemptible (voluntary only), but the important part is that KVM
> will drop mmu_lock if there is contention (which is a "requirement" for the bug
> that Yan encountered).
For posterity, the above is wrong. Volutary preemption isn't _supposed_ to enable
yielding of contended spinlocks/rwlocks, but due to a bug with dynamic preemption,
the behavior got enabled for all preempt models:
https://lore.kernel.org/all/20240110214723.695930-1-seanjc@google.com
next prev parent reply other threads:[~2024-01-11 15:55 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-12 16:37 [Bug 218259] New: High latency in KVM guests bugzilla-daemon
2023-12-13 16:54 ` Sean Christopherson
2023-12-13 16:54 ` [Bug 218259] " bugzilla-daemon
2023-12-14 7:14 ` bugzilla-daemon
2023-12-18 17:07 ` Sean Christopherson
2023-12-14 7:15 ` bugzilla-daemon
2023-12-14 7:16 ` bugzilla-daemon
2023-12-18 17:07 ` bugzilla-daemon
2024-01-11 15:55 ` Sean Christopherson [this message]
2023-12-19 14:09 ` bugzilla-daemon
2023-12-19 15:16 ` Sean Christopherson
2023-12-19 15:16 ` bugzilla-daemon
2024-01-11 15:55 ` bugzilla-daemon
2024-01-16 13:29 ` bugzilla-daemon
2024-01-17 1:05 ` Sean Christopherson
2024-01-17 1:05 ` bugzilla-daemon
2024-01-17 14:04 ` bugzilla-daemon
2024-11-05 0:27 ` bugzilla-daemon
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