This is a fix for my earlier patch: "virtio: Add memory statistics reporting to
the balloon driver (V4)".
I discovered that all_vm_events() can sleep and therefore stats collection
cannot be done in interrupt context. One solution is to handle the interrupt
by noting that stats need to be collected and waking the existing vballoon
kthread which will complete the work via stats_handle_request(). Rusty, is
this a saner way of doing business?
There is one issue that I would like a broader opinion on. In stats_request, I
update vb->need_stats_update and then wake up the kthread. The kthread uses
vb->need_stats_update as a condition variable. Do I need a memory barrier
between the update and wake_up to ensure that my kthread sees the correct
value? My testing suggests that it is not needed but I would like some
confirmation from the experts.
Signed-off-by: Adam Litke <agl@us.ibm.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Anthony Liguori <aliguori@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changes since V3:
- Do not do endian conversions as they will be done in the host
- Report stats that reference a quantity of memory in bytes
- Minor coding style updates
Changes since V2:
- Increase stat field size to 64 bits
- Report all sizes in kb (not pages)
- Drop anon_pages stat and fix endianness conversion
Changes since V1:
- Use a virtqueue instead of the device config space
When using ballooning to manage overcommitted memory on a host, a system for
guests to communicate their memory usage to the host can provide information
that will minimize the impact of ballooning on the guests. The current method
employs a daemon running in each guest that communicates memory statistics to a
host daemon at a specified time interval. The host daemon aggregates this
information and inflates and/or deflates balloons according to the level of
host memory pressure. This approach is effective but overly complex since a
daemon must be installed inside each guest and coordinated to communicate with
the host. A simpler approach is to collect memory statistics in the virtio
balloon driver and communicate them directly to the hypervisor.
This patch enables the guest-side support by adding stats collection and
reporting to the virtio balloon driver.
Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: Anthony Liguori <anthony@codemonkey.ws>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor fixes)
Fix fixes the following warnings by renaming the driver structures to be
suffixed with _driver.
WARNING: drivers/virtio/virtio_balloon.o(.data+0x88): Section mismatch in reference from the variable virtio_balloon to the function .devexit.text:virtballoon_remove()
WARNING: drivers/char/hw_random/virtio-rng.o(.data+0x88): Section mismatch in reference from the variable virtio_rng to the function .devexit.text:virtrng_remove()
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The function virtballoon_remove is used only wrapped by __devexit_p so
define it using __devexit.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Rusty,
commit 3ca4f5ca73
virtio: add virtio IDs file
moved all device IDs into a single file. While the change itself is
a very good one, it can break userspace applications. For example
if a userspace tool wanted to get the ID of virtio_net it used to
include virtio_net.h. This does no longer work, since virtio_net.h
does not include virtio_ids.h.
This patch moves all "#include <linux/virtio_ids.h>" from the C
files into the header files, making the header files compatible with
the old ones.
In addition, this patch exports virtio_ids.h to userspace.
CC: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Virtio IDs are spread all over the tree which makes assigning new IDs
bothersome. Putting them together should make the process less error-prone.
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This API change means that virtio_net can tell how much capacity
remains for buffers. It's necessarily fuzzy, since
VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors
in one, *if* we can kmalloc.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dinesh Subhraveti <dineshs@us.ibm.com>
This replaces find_vq/del_vq with find_vqs/del_vqs virtio operations,
and updates all drivers. This is needed for MSI support, because MSI
needs to know the total number of vectors upfront.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ lguest/9p compile fixes)
Add a linked list of all virtqueues for a virtio device: this helps for
debugging and is also needed for upcoming interface change.
Also, add a "name" field for clearer debug messages.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Break out of wait_event_interruptible() if freezing has been requested,
in the vballoon thread. Without this change vballoon refuses to stop and
the system can't suspend.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Make the balloon interface always use 4K pages, and convert Linux pfns if
necessary. This patch assumes that Linux's PAGE_SHIFT will never be less than
12.
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (modified)
Both v and vb->num_pages are u32 and unsigned int respectively. If v is less
than vb->num_pages (and it is, when deflating the balloon), the result is a
very large 32-bit number. Since we're returning a s64, instead of getting the
same negative number we desire, we get a very large positive number.
This handles the case where v < vb->num_pages and ensures we get a small,
negative, s64 as the result.
Rusty: please push this for 2.6.27-rc4. It's probably appropriate for the
stable tree too as it will cause an unexpected OOM when ballooning.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (simplified)
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API: in particular, we assume that feature
negotiation is complete once a driver's probe function returns.
There is nothing in the API to require this, however, and even I
didn't notice when it was violated.
So instead, we require the driver to specify what features it supports
in a table, we can then move the feature negotiation into the virtio
core. The intersection of device and driver features are presented in
a new 'features' bitmap in the struct virtio_device.
Note that this highlights the difference between Linux unsigned-long
bitmaps where each unsigned long is in native endian, and a
straight-forward little-endian array of bytes.
Drivers can still remove feature bits in their probe routine if they
really have to.
API changes:
- dev->config->feature() no longer gets and acks a feature.
- drivers should advertise their features in the 'feature_table' field
- use virtio_has_feature() for extra sanity when checking feature bits
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
A recent proposed feature addition to the virtio block driver revealed
some flaws in the API, in particular how easy it is to break big
endian machines.
The virtio config space was originally chosen to be little-endian,
because we thought the config might be part of the PCI config space
for virtio_pci. It's actually a separate mmio region, so that
argument holds little water; as only x86 is currently using the virtio
mechanism, we can change this (but must do so now, before the
impending s390 merge).
API changes:
- __virtio_config_val() just becomes a striaght vdev->config_get() call.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
If the host asks for a huge target towards_target() can overflow, and
we up oops as we try to release more pages than we have. The simple
fix is to use a 64-bit value.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Include linux/delay.h to fix compiler error:
drivers/virtio/virtio_balloon.c: In function 'fill_balloon':
drivers/virtio/virtio_balloon.c:98: error: implicit declaration of function 'msleep'
Signed-off-by: Johann Felix Soden <johfel@users.sourceforge.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After discussions with Anthony Liguori, it seems that the virtio
balloon can be made even simpler. Here's my attempt.
The device configuration tells the driver how much memory it should
take from the guest (ie. balloon size). The guest feeds the page
numbers it has taken via one virtqueue.
A second virtqueue feeds the page numbers the driver wants back: if
the device has the VIRTIO_BALLOON_F_MUST_TELL_HOST bit, then this
queue is compulsory, otherwise it's advisory (and the guest can simply
fault the pages back in).
This driver can be enhanced later to deflate the balloon via a
shrinker, oom callback or we could even go for a complete set of
in-guest regulators.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
