From: Paolo Bonzini <pbonzini@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-kernel@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
"Jonathan Corbet" <corbet@lwn.net>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org,
qemu-devel@nongnu.org
Subject: Re: [PATCH] kvm: rename HINTS_DEDICATED to KVM_HINTS_REALTIME
Date: Fri, 18 May 2018 19:17:43 +0200 [thread overview]
Message-ID: <9d528020-87f6-a600-9d08-02c88d20b18c@redhat.com> (raw)
In-Reply-To: <20180518160431.GX25013@localhost.localdomain>
On 18/05/2018 18:04, Eduardo Habkost wrote:
>> Without mlock you should always use pv spinlocks.
>>
>> Otherwise you risk blocking on a lock taken by
>> a VCPU that is in turn blocked on IO, where the IO
>> is not completing because CPU is being used up
>> spinning.
>
> So the stronger guarantee seems necessary.
>
> Now what should host userspace do if the user is trying to run an
> existing configuration where the CPUID hint was set but memory is
> not pinned?
As mentioned elsewhere in the thread, there are many ways to pin memory,
and mlock is not always necessary. However, I agree with Michael in
making the hint provide a stronger guarantee.
Paolo
next prev parent reply other threads:[~2018-05-18 17:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-17 14:54 [PATCH] kvm: rename HINTS_DEDICATED to KVM_HINTS_REALTIME Michael S. Tsirkin
2018-05-17 16:05 ` Paolo Bonzini
2018-05-17 18:46 ` Eduardo Habkost
2018-05-17 19:55 ` Michael S. Tsirkin
2018-05-18 16:04 ` Eduardo Habkost
2018-05-18 17:01 ` Michael S. Tsirkin
2018-05-18 17:13 ` Eduardo Habkost
2018-05-18 17:18 ` Paolo Bonzini
2018-05-18 17:54 ` Eduardo Habkost
2018-05-18 17:17 ` Paolo Bonzini [this message]
2018-05-18 9:41 ` Paolo Bonzini
2018-05-18 12:47 ` Michael S. Tsirkin
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