From: Paolo Bonzini <pbonzini@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, andrey@xdel.ru
Subject: Re: [PATCH 3/5] vhost: support upto 509 memory regions
Date: Mon, 22 Jun 2015 11:45:59 +0200 [thread overview]
Message-ID: <5587D957.90007@redhat.com> (raw)
In-Reply-To: <20150622091027.582a1549@nial.brq.redhat.com>
On 22/06/2015 09:10, Igor Mammedov wrote:
> So far HVA is unusable even if we will make this assumption and let guest crash.
> virt_net doesn't work with it anyway,
> translation of GPA to HVA for descriptors works as expected (correctly)
> but vhost+HVA hack backed virtio still can't send/received packets.
>
> That's why I prefer to merge kernel solution first as a stable and
> not introducing any issues solution. And work on userspace approach on
> top of that.
Also, let's do some math.
Let's assume 3 network devices per VM, one vhost device per queue, one
queue per VCPU per network device. Let's assume the host is
overcommitted 3:1.
Thus we have 3*3=9 times vhost devices as we have physical CPUs.
We're thus talking about 108K per physical CPU.
>From a relative point of view, and assuming 1 GB of memory per physical
CPU (pretty low amount if you're overcommitting CPU 3:1), this is 0.01%
of the total memory.
>From an absolute point of view, it takes a system with 60 physical CPUs
to reach the same memory usage as the vmlinuz binary of a typical distro
kernel (not counting the modules).
Paolo
> Hopefully it could be done but we still would need time
> to iron out side effects/issues it causes or could cause so that
> fix became stable enough for production.
>
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WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, andrey@xdel.ru
Subject: Re: [PATCH 3/5] vhost: support upto 509 memory regions
Date: Mon, 22 Jun 2015 11:45:59 +0200 [thread overview]
Message-ID: <5587D957.90007@redhat.com> (raw)
In-Reply-To: <20150622091027.582a1549@nial.brq.redhat.com>
On 22/06/2015 09:10, Igor Mammedov wrote:
> So far HVA is unusable even if we will make this assumption and let guest crash.
> virt_net doesn't work with it anyway,
> translation of GPA to HVA for descriptors works as expected (correctly)
> but vhost+HVA hack backed virtio still can't send/received packets.
>
> That's why I prefer to merge kernel solution first as a stable and
> not introducing any issues solution. And work on userspace approach on
> top of that.
Also, let's do some math.
Let's assume 3 network devices per VM, one vhost device per queue, one
queue per VCPU per network device. Let's assume the host is
overcommitted 3:1.
Thus we have 3*3=9 times vhost devices as we have physical CPUs.
We're thus talking about 108K per physical CPU.
>From a relative point of view, and assuming 1 GB of memory per physical
CPU (pretty low amount if you're overcommitting CPU 3:1), this is 0.01%
of the total memory.
>From an absolute point of view, it takes a system with 60 physical CPUs
to reach the same memory usage as the vmlinuz binary of a typical distro
kernel (not counting the modules).
Paolo
> Hopefully it could be done but we still would need time
> to iron out side effects/issues it causes or could cause so that
> fix became stable enough for production.
>
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
next prev parent reply other threads:[~2015-06-22 9:46 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 16:33 [PATCH 0/5] vhost: support upto 509 memory regions Igor Mammedov
2015-06-16 16:33 ` [PATCH 1/5] vhost: use binary search instead of linear in find_region() Igor Mammedov
2015-06-16 21:07 ` Michael S. Tsirkin
2015-06-16 21:13 ` Igor Mammedov
2015-06-16 16:33 ` [PATCH 2/5] vhost: extend memory regions allocation to vmalloc Igor Mammedov
2015-06-16 16:33 ` [PATCH 3/5] vhost: support upto 509 memory regions Igor Mammedov
2015-06-16 21:14 ` Michael S. Tsirkin
2015-06-16 22:00 ` Igor Mammedov
2015-06-17 6:34 ` Michael S. Tsirkin
2015-06-17 7:28 ` Igor Mammedov
2015-06-17 7:39 ` Michael S. Tsirkin
2015-06-17 8:54 ` Igor Mammedov
2015-06-17 10:11 ` Michael S. Tsirkin
2015-06-17 10:37 ` Igor Mammedov
2015-06-17 10:46 ` Michael S. Tsirkin
2015-06-17 11:48 ` Igor Mammedov
2015-06-17 11:51 ` Michael S. Tsirkin
2015-06-17 12:23 ` Igor Mammedov
2015-06-17 13:13 ` Michael S. Tsirkin
2015-06-17 13:20 ` Paolo Bonzini
2015-06-17 14:32 ` Michael S. Tsirkin
2015-06-17 15:12 ` Igor Mammedov
2015-06-17 15:38 ` Michael S. Tsirkin
2015-06-17 16:09 ` Igor Mammedov
2015-06-17 16:30 ` Michael S. Tsirkin
2015-06-17 16:31 ` Paolo Bonzini
2015-06-17 16:34 ` Michael S. Tsirkin
2015-06-17 16:38 ` Paolo Bonzini
2015-06-17 16:41 ` Michael S. Tsirkin
2015-06-17 16:47 ` Paolo Bonzini
2015-06-17 17:32 ` Igor Mammedov
2015-06-17 19:11 ` Michael S. Tsirkin
2015-06-17 17:30 ` Igor Mammedov
2015-06-18 9:12 ` Igor Mammedov
2015-06-18 9:50 ` Michael S. Tsirkin
2015-06-18 10:03 ` Paolo Bonzini
2015-06-18 11:39 ` Igor Mammedov
2015-06-18 11:41 ` Michael S. Tsirkin
2015-06-18 11:50 ` Paolo Bonzini
2015-06-18 13:19 ` Michael S. Tsirkin
2015-06-18 13:46 ` Paolo Bonzini
2015-06-18 14:47 ` Michael S. Tsirkin
2015-06-18 15:54 ` Igor Mammedov
2015-06-18 16:02 ` Paolo Bonzini
2015-06-19 7:56 ` Michael S. Tsirkin
2015-06-19 7:57 ` Paolo Bonzini
2015-06-19 8:05 ` Michael S. Tsirkin
2015-06-19 8:52 ` Paolo Bonzini
2015-06-19 10:14 ` Michael S. Tsirkin
2015-06-19 10:44 ` Paolo Bonzini
2015-06-19 13:34 ` Michael S. Tsirkin
2015-06-19 13:34 ` Michael S. Tsirkin
2015-06-19 15:19 ` Paolo Bonzini
2015-06-19 15:19 ` Paolo Bonzini
2015-06-19 16:20 ` Michael S. Tsirkin
2015-06-19 16:20 ` Michael S. Tsirkin
2015-06-19 16:26 ` Paolo Bonzini
2015-06-19 16:26 ` Paolo Bonzini
2015-06-19 16:33 ` Michael S. Tsirkin
2015-06-19 16:33 ` Michael S. Tsirkin
2015-06-19 16:44 ` Paolo Bonzini
2015-06-19 16:44 ` Paolo Bonzini
2015-06-22 7:10 ` Igor Mammedov
2015-06-22 7:10 ` Igor Mammedov
2015-06-22 9:45 ` Paolo Bonzini [this message]
2015-06-22 9:45 ` Paolo Bonzini
2015-06-19 16:45 ` Michael S. Tsirkin
2015-06-19 16:45 ` Michael S. Tsirkin
2015-06-19 16:50 ` Paolo Bonzini
2015-06-19 16:50 ` Paolo Bonzini
2015-06-18 12:02 ` Igor Mammedov
2015-06-17 8:53 ` Paolo Bonzini
2015-06-16 16:33 ` [PATCH 4/5] vhost: add per VQ memory region caching Igor Mammedov
2015-06-16 16:33 ` [PATCH 5/5] vhost: translate_desc: optimization for desc.len < region size Igor Mammedov
2015-06-16 21:11 ` Michael S. Tsirkin
2015-06-16 21:16 ` [PATCH 0/5] vhost: support upto 509 memory regions Michael S. Tsirkin
2015-06-16 22:19 ` Igor Mammedov
2015-06-17 6:31 ` Michael S. Tsirkin
2015-06-17 7:33 ` Igor Mammedov
2015-06-17 7:40 ` Michael S. Tsirkin
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