From: "Michael S. Tsirkin" <mst@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
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
Subject: Re: [PATCH] kvm: rename HINTS_DEDICATED to KVM_HINTS_REALTIME
Date: Fri, 18 May 2018 15:47:53 +0300 [thread overview]
Message-ID: <20180518154721-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <a95b2a12-f3a9-b930-49fe-46c2278df34d@redhat.com>
On Fri, May 18, 2018 at 11:41:23AM +0200, Paolo Bonzini wrote:
> On 17/05/2018 20:46, Eduardo Habkost wrote:
> > My understanding of the original patch is that the intention is
> > to tell the guest that it is very unlikely to be preempted, so it
> > can choose a more appropriate spinlock implementation. This
> > description implies that the guest will never be preempted, which
> > is much stronger guarantee.
> >
> > Isn't this new description incompatible with existing usage of
> > the hint, which might include people who just use vCPU pinning
> > but no mlock?
>
> If you use hugetlbfs and vhost-user you don't really need mlock for the
> QEMU process, do you? The QEMU process is not doing much in that case
> and hugetlbfs gives you pinned memory automatically.
>
> Paolo
Same with PCI device passthrough: VFIO pins all guest memory right now.
--
MST
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WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
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
Subject: Re: [PATCH] kvm: rename HINTS_DEDICATED to KVM_HINTS_REALTIME
Date: Fri, 18 May 2018 15:47:53 +0300 [thread overview]
Message-ID: <20180518154721-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <a95b2a12-f3a9-b930-49fe-46c2278df34d@redhat.com>
On Fri, May 18, 2018 at 11:41:23AM +0200, Paolo Bonzini wrote:
> On 17/05/2018 20:46, Eduardo Habkost wrote:
> > My understanding of the original patch is that the intention is
> > to tell the guest that it is very unlikely to be preempted, so it
> > can choose a more appropriate spinlock implementation. This
> > description implies that the guest will never be preempted, which
> > is much stronger guarantee.
> >
> > Isn't this new description incompatible with existing usage of
> > the hint, which might include people who just use vCPU pinning
> > but no mlock?
>
> If you use hugetlbfs and vhost-user you don't really need mlock for the
> QEMU process, do you? The QEMU process is not doing much in that case
> and hugetlbfs gives you pinned memory automatically.
>
> Paolo
Same with PCI device passthrough: VFIO pins all guest memory right now.
--
MST
next prev parent reply other threads:[~2018-05-18 12:48 UTC|newest]
Thread overview: 30+ 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 14:54 ` Michael S. Tsirkin
2018-05-17 16:05 ` Paolo Bonzini
2018-05-17 16:05 ` Paolo Bonzini
2018-05-17 18:46 ` Eduardo Habkost
2018-05-17 18:46 ` Eduardo Habkost
2018-05-17 19:55 ` Michael S. Tsirkin
2018-05-17 19:55 ` Michael S. Tsirkin
2018-05-18 16:04 ` Eduardo Habkost
2018-05-18 16:04 ` [Qemu-devel] " Eduardo Habkost
2018-05-18 16:04 ` Eduardo Habkost
2018-05-18 17:01 ` Michael S. Tsirkin
2018-05-18 17:01 ` [Qemu-devel] " Michael S. Tsirkin
2018-05-18 17:01 ` Michael S. Tsirkin
2018-05-18 17:13 ` Eduardo Habkost
2018-05-18 17:13 ` [Qemu-devel] " Eduardo Habkost
2018-05-18 17:13 ` Eduardo Habkost
2018-05-18 17:18 ` Paolo Bonzini
2018-05-18 17:18 ` [Qemu-devel] " Paolo Bonzini
2018-05-18 17:18 ` Paolo Bonzini
2018-05-18 17:54 ` Eduardo Habkost
2018-05-18 17:54 ` [Qemu-devel] " Eduardo Habkost
2018-05-18 17:54 ` Eduardo Habkost
2018-05-18 17:17 ` Paolo Bonzini
2018-05-18 17:17 ` [Qemu-devel] " Paolo Bonzini
2018-05-18 17:17 ` Paolo Bonzini
2018-05-18 9:41 ` Paolo Bonzini
2018-05-18 9:41 ` Paolo Bonzini
2018-05-18 12:47 ` Michael S. Tsirkin [this message]
2018-05-18 12:47 ` Michael S. Tsirkin
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