From: Frank Swiderski <fes@google.com>
To: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
"Michael S. Tsirkin" <mst@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
mikew@google.com, Ying Han <yinghan@google.com>,
Rafael Aquini <aquini@redhat.com>
Subject: Re: [PATCH] Add a page cache-backed balloon device driver.
Date: Tue, 26 Jun 2012 14:31:26 -0700 [thread overview]
Message-ID: <CAK+C7kWKtoYC=1fBQ45RTFfNc3p2PwZbLMOefMTtzOfsqe_k8w@mail.gmail.com> (raw)
In-Reply-To: <4FEA1E2E.4020806@redhat.com>
On Tue, Jun 26, 2012 at 1:40 PM, Rik van Riel <riel@redhat.com> wrote:
> On 06/26/2012 04:32 PM, Frank Swiderski wrote:
>>
>> This implementation of a virtio balloon driver uses the page cache to
>> "store" pages that have been released to the host. The communication
>> (outside of target counts) is one way--the guest notifies the host when
>> it adds a page to the page cache, allowing the host to madvise(2) with
>> MADV_DONTNEED. Reclaim in the guest is therefore automatic and implicit
>> (via the regular page reclaim). This means that inflating the balloon
>> is similar to the existing balloon mechanism, but the deflate is
>> different--it re-uses existing Linux kernel functionality to
>> automatically reclaim.
>>
>> Signed-off-by: Frank Swiderski<fes@google.com>
>
>
> It is a great idea, but how can this memory balancing
> possibly work if someone uses memory cgroups inside a
> guest?
Thanks and good point--this isn't something that I considered in the
implementation.
> Having said that, we currently do not have proper
> memory reclaim balancing between cgroups at all, so
> requiring that of this balloon driver would be
> unreasonable.
>
> The code looks good to me, my only worry is the
> code duplication. We now have 5 balloon drivers,
> for 4 hypervisors, all implementing everything
> from scratch...
Do you have any recommendations on this? I could (I think reasonably
so) modify the existing virtio_balloon.c and have it change behavior
based on a feature bit or other configuration. I'm not sure that
really addresses the root of what you're pointing out--it's still
adding a different implementation, but doing so as an extension of an
existing one.
fes
WARNING: multiple messages have this Message-ID (diff)
From: Frank Swiderski <fes@google.com>
To: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Rafael Aquini <aquini@redhat.com>,
kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Ying Han <yinghan@google.com>,
mikew@google.com
Subject: Re: [PATCH] Add a page cache-backed balloon device driver.
Date: Tue, 26 Jun 2012 14:31:26 -0700 [thread overview]
Message-ID: <CAK+C7kWKtoYC=1fBQ45RTFfNc3p2PwZbLMOefMTtzOfsqe_k8w@mail.gmail.com> (raw)
In-Reply-To: <4FEA1E2E.4020806@redhat.com>
On Tue, Jun 26, 2012 at 1:40 PM, Rik van Riel <riel@redhat.com> wrote:
> On 06/26/2012 04:32 PM, Frank Swiderski wrote:
>>
>> This implementation of a virtio balloon driver uses the page cache to
>> "store" pages that have been released to the host. The communication
>> (outside of target counts) is one way--the guest notifies the host when
>> it adds a page to the page cache, allowing the host to madvise(2) with
>> MADV_DONTNEED. Reclaim in the guest is therefore automatic and implicit
>> (via the regular page reclaim). This means that inflating the balloon
>> is similar to the existing balloon mechanism, but the deflate is
>> different--it re-uses existing Linux kernel functionality to
>> automatically reclaim.
>>
>> Signed-off-by: Frank Swiderski<fes@google.com>
>
>
> It is a great idea, but how can this memory balancing
> possibly work if someone uses memory cgroups inside a
> guest?
Thanks and good point--this isn't something that I considered in the
implementation.
> Having said that, we currently do not have proper
> memory reclaim balancing between cgroups at all, so
> requiring that of this balloon driver would be
> unreasonable.
>
> The code looks good to me, my only worry is the
> code duplication. We now have 5 balloon drivers,
> for 4 hypervisors, all implementing everything
> from scratch...
Do you have any recommendations on this? I could (I think reasonably
so) modify the existing virtio_balloon.c and have it change behavior
based on a feature bit or other configuration. I'm not sure that
really addresses the root of what you're pointing out--it's still
adding a different implementation, but doing so as an extension of an
existing one.
fes
next prev parent reply other threads:[~2012-06-26 21:31 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-26 20:32 [PATCH] Add a page cache-backed balloon device driver Frank Swiderski
2012-06-26 20:40 ` Rik van Riel
2012-06-26 20:40 ` Rik van Riel
2012-06-26 21:31 ` Frank Swiderski [this message]
2012-06-26 21:31 ` Frank Swiderski
2012-06-26 21:45 ` Rik van Riel
2012-06-26 21:45 ` Rik van Riel
2012-06-26 23:45 ` Frank Swiderski
2012-06-27 9:04 ` Michael S. Tsirkin
2012-06-27 9:04 ` Michael S. Tsirkin
2012-06-26 21:47 ` Michael S. Tsirkin
2012-06-26 21:47 ` Michael S. Tsirkin
2012-06-26 23:21 ` Frank Swiderski
2012-06-26 23:21 ` Frank Swiderski
2012-06-27 9:02 ` Michael S. Tsirkin
2012-06-27 9:02 ` Michael S. Tsirkin
2012-07-02 0:29 ` Rusty Russell
2012-07-02 0:29 ` Rusty Russell
2012-09-03 6:35 ` Paolo Bonzini
2012-09-03 6:35 ` Paolo Bonzini
2012-09-06 1:35 ` Rusty Russell
2012-09-06 1:35 ` Rusty Russell
2012-06-26 21:41 ` Michael S. Tsirkin
2012-06-26 21:41 ` Michael S. Tsirkin
2012-06-27 2:56 ` Rusty Russell
2012-06-27 2:56 ` Rusty Russell
2012-06-27 15:48 ` Frank Swiderski
2012-06-27 15:48 ` Frank Swiderski
2012-06-27 16:06 ` Michael S. Tsirkin
2012-06-27 16:06 ` Michael S. Tsirkin
2012-06-27 16:08 ` Frank Swiderski
2012-06-27 16:08 ` Frank Swiderski
2012-06-27 9:40 ` Amit Shah
2012-06-27 9:40 ` Amit Shah
2012-08-30 8:57 ` Michael S. Tsirkin
2012-08-30 8:57 ` Michael S. Tsirkin
2012-09-03 15:09 ` Avi Kivity
2012-09-03 15:09 ` Avi Kivity
2012-09-10 9:05 ` Michael S. Tsirkin
2012-09-10 9:05 ` Michael S. Tsirkin
2012-09-10 17:37 ` Mike Waychison
2012-09-10 17:37 ` Mike Waychison
2012-09-10 18:04 ` Rik van Riel
2012-09-10 18:04 ` Rik van Riel
2012-09-10 18:29 ` Mike Waychison
2012-09-10 18:29 ` Mike Waychison
2012-09-10 19:59 ` Michael S. Tsirkin
2012-09-10 19:59 ` Michael S. Tsirkin
2012-09-10 19:59 ` Michael S. Tsirkin
2012-09-10 20:49 ` Mike Waychison
2012-09-10 20:49 ` Mike Waychison
2012-09-10 21:10 ` Michael S. Tsirkin
2012-09-10 21:10 ` Michael S. Tsirkin
2012-10-30 15:29 ` Michael S. Tsirkin
2012-10-30 15:29 ` Michael S. Tsirkin
2012-10-30 16:25 ` Mike Waychison
2012-10-30 16:25 ` Mike Waychison
2012-09-12 5:25 ` Rusty Russell
2012-09-12 5:25 ` Rusty Russell
2012-06-26 20:32 Frank Swiderski
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