From: Rusty Russell <rusty@rustcorp.com.au>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org,
Dave Hansen <dave@linux.vnet.ibm.com>
Subject: Re: [RFC][PATCH] virtio balloon: kill tell-host-first logic
Date: Sun, 10 Apr 2011 08:18:22 +0930 [thread overview]
Message-ID: <87ei5bdosp.fsf@rustcorp.com.au> (raw)
In-Reply-To: <20110407174325.ED21C82B@kernel>
On Thu, 07 Apr 2011 10:43:25 -0700, Dave Hansen <dave@linux.vnet.ibm.com> wrote:
>
> The virtio balloon driver has a VIRTIO_BALLOON_F_MUST_TELL_HOST
> feature bit. Whenever the bit is set, we must always tell the
> host before we free pages back to the allocator. Without this
> we might free a page (and have another user touch it) while the
> hypervisor is unprepared for it.
>
> But, if the bit is _not_ set, we are under no obligation to
> reverse the order. Furthermore, all modern qemus set this bit.
> So, the "tell second" code is completely unused and untestable.
> Quoting Anthony: "untested code is broken code".
>
> This _also_ means that we don't have to preserve a pfn list
> after the pages are freed, which should let us get rid of some
> temporary storage (vb->pfns) eventually.
>
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Thanks, applied!
Rusty.
next prev parent reply other threads:[~2011-04-10 0:42 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-07 17:43 [RFC][PATCH] virtio balloon: kill tell-host-first logic Dave Hansen
2011-04-09 22:48 ` Rusty Russell [this message]
2011-04-09 22:48 ` Rusty Russell
2011-04-11 11:01 ` Michael S. Tsirkin
2011-04-11 11:01 ` Michael S. Tsirkin
2011-04-11 22:11 ` Dave Hansen
2011-04-12 5:43 ` Amit Shah
2011-04-12 5:43 ` Amit Shah
2011-04-12 16:22 ` Dave Hansen
2011-04-12 16:22 ` Dave Hansen
2011-04-12 16:43 ` Amit Shah
2011-04-14 20:28 ` Dave Hansen
2011-04-15 10:39 ` Amit Shah
2011-04-15 10:39 ` Amit Shah
2011-04-14 20:28 ` Dave Hansen
2011-04-12 16:43 ` Amit Shah
2011-04-14 11:37 ` Rusty Russell
2011-04-14 20:30 ` Dave Hansen
2011-04-14 20:30 ` Dave Hansen
2011-04-19 1:25 ` Rusty Russell
2011-04-19 1:25 ` Rusty Russell
2011-04-14 11:37 ` Rusty Russell
2011-04-11 22:11 ` Dave Hansen
-- strict thread matches above, loose matches on Subject: below --
2011-04-07 17:43 Dave Hansen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87ei5bdosp.fsf@rustcorp.com.au \
--to=rusty@rustcorp.com.au \
--cc=dave@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@redhat.com \
--cc=virtualization@lists.linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.