It is useful to expose how many times the balloon resets. If it happens
more than very rarely - this is an indication for a problem.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change all the remaining return values to int to avoid mistakes. Reduce
indentation when possible.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In preparation for supporting compaction and OOM notification, this
patch reworks the inflate/deflate loops. The main idea is to separate
the allocation, communication with the hypervisor, and the handling of
errors from each other. Doing will allow us to perform concurrent
inflation and deflation, excluding the actual communication with the
hypervisor.
To do so, we need to get rid of the remaining global state that is kept
in the balloon struct, specifically the refuse_list. When the VM
communicates with the hypervisor, it does not free or put back pages
to the balloon list and instead only moves the pages whose status
indicated failure into a refuse_list on the stack. Once the operation
completes, the inflation or deflation functions handle the list
appropriately.
As we do that, we can consolidate the communication with the hypervisor
for both the lock and unlock operations into a single function. We also
reuse the deflation function for popping the balloon.
As a preparation for preventing races, we hold a spinlock when the
communication actually takes place, and use atomic operations for
updating the balloon size. The balloon page list is still racy and will
be handled in the next patch.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To allow the balloon statistics to be updated concurrently, we change
the statistics to be held per core and aggregate it when needed.
To avoid the memory overhead of keeping the statistics per core, and
since it is likely not used by most users, we start updating the
statistics only after the first use. A read-write semaphore is used to
protect the statistics initialization and avoid races. This semaphore is
(and will) be used to protect configuration changes during reset.
While we are at it, address some other issues: change the statistics
update to inline functions instead of define; use ulong for saving the
statistics; and clean the statistics printouts.
Note that this patch changes the format of the outputs. If there are any
automatic tools that use the statistics, they might fail.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As we want to leave as little as possible on the global balloon
structure, to avoid possible future races, we want to get rid sysinfo.
We can actually get the total_ram directly, and simplify the logic of
vmballoon_send_get_target() a little.
While we are doing that, let's return int and avoid mistakes due to
bool/int conversions.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The required change in the balloon size is currently computed in
vmballoon_work(), vmballoon_inflate() and vmballoon_deflate(). Refactor
it to simplify the next patches.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The name of the macro'd VMW_BALLOON_2M_SHIFT is misleading. The value
reflects 2M huge-page order. Unfortunately, we cannot use
HPAGE_PMD_ORDER, since it is not defined when transparent huge-pages are
off, so we need to define our own one.
Rename it to VMW_BALLOON_2M_ORDER. No functional change.
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, when the hypervisor rejects a page during lock operation, the
VM treats pages differently according to the error-code: in certain
cases the page is immediately freed, and in others it is put on a
rejection list and only freed later.
The behavior does not make too much sense. If the page is freed
immediately it is very likely to be used again in the next batch of
allocations, and be rejected again.
In addition, for support of compaction and OOM notifiers, we wish to
separate the logic that communicates with the hypervisor (as well as
analyzes the status of each page) from the logic that allocates or free
pages.
Treat all errors the same way, queuing the pages on the refuse list.
Move to the next allocation size (4k) when too many pages are refused.
Free the refused pages when moving to the next size to avoid situations
in which too much memory is waiting to be freed on the refused list.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The current abstractions for batch vs single operations seem suboptimal
and complicate the implementation of additional features (OOM,
compaction).
The immediate problem of the current abstractions is that they cause
differences in how operations are handled when batching is on or off.
For example, the refused_alloc counter is not updated when batching is
on. These discrepancies are caused by code redundancies.
Instead, this patch presents three type of operations, according to
whether batching is on or off: (1) add page, (2) communication with the
hypervisor and (3) retrieving the status of a page.
To avoid the overhead of virtual functions, and since we do not expect
additional interfaces for communication with the hypervisor, we use
static keys instead of virtual functions.
Finally, while we are at it, change vmballoon_init_batching() to return
int instead of bool, to be consistent in the return type and avoid
potential coding errors.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Splitting the allocations between sleeping and non-sleeping made some
sort of sense as long as rate-limiting was enabled. Now that it is
removed, we need to decide - either we want sleeping allocations or not.
Since no other Linux balloon driver (hv, Xen, virtio) uses sleeping
allocations, use the same approach.
We do distinguish, however, between 2MB allocations and 4kB allocations
and prevent reclamation on 2MB. In both cases, we avoid using emergency
low-memory pools, as it may cause undesired effects.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The use of accessors for batch entries complicates the code and makes it
less readable. Remove it an instead use bit-fields.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The lock and unlock code paths are very similar, so avoid the duplicate
code by merging them together.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that we have a single point, unify the tracing and collecting the
statistics for commands and their failure. While it might somewhat
reduce the control over debugging, it cleans the code a lot.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
By inlining the hypercall interface, we can unify several operations
into one central point in the code:
- Updating the target.
- Updating when a reset is needed.
- Update statistics (which will be done later in the patch-set).
- Print debug-messages (although they cannot be enabled as selectively).
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Embarrassingly, the recent fix introduced worse problem than it solved,
causing the balloon not to inflate. The VM informed the hypervisor that
the pages for lock/unlock are sitting in the wrong address, as it used
the page that is used the uninitialized page variable.
Fixes: b23220fe05 ("vmw_balloon: fixing double free when batching mode is off")
Cc: stable@vger.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Removing the GPL wording and replace it with an SPDX tag. The immediate
trigger for doing it now is the need to remove the list of maintainers
from the source file, as the maintainer list changed.
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit 33d268ed00 ("VMware balloon: Do not limit the amount of
frees and allocations in non-sleep mode."), the allocations are not
increased, and therefore balloon inflation rate limiting is in practice
broken.
While we can restore rate limiting, in practice we see that it can
result in adverse effect, as the hypervisor throttles down the VM if it
does not respond well enough, or alternatively causes it to perform very
poorly as the host swaps out the VM memory. Throttling the VM down can
even have a cascading effect, in which the VM reclaims memory even
slower and consequentially throttled down even further.
We therefore remove all the rate limiting mechanisms, including the slow
allocation cycles, as they are likely to do more harm than good.
Fixes: 33d268ed00 ("VMware balloon: Do not limit the amount of frees and allocations in non-sleep mode.")
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, when all modules, including VMCI and VMware balloon are built
into the kernel, the initialization of the balloon happens before the
VMCI is probed. As a result, the balloon fails to initialize the VMCI
doorbell, which it uses to get asynchronous requests for balloon size
changes.
The problem can be seen in the logs, in the form of the following
message:
"vmw_balloon: failed to initialize vmci doorbell"
The driver would work correctly but slightly less efficiently, probing
for requests periodically. This patch changes the balloon to be
initialized using late_initcall() instead of module_init() to address
this issue. It does not address a situation in which VMCI is built as a
module and the balloon is built into the kernel.
Fixes: 48e3d668b7 ("VMware balloon: Enable notification via VMCI")
Cc: stable@vger.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When vmballoon_vmci_init() sets a doorbell using VMCI_DOORBELL_SET, for
some reason it does not consider the status and looks at the result.
However, the hypervisor does not update the result - it updates the
status. This might cause VMCI doorbell not to be enabled, resulting in
degraded performance.
Fixes: 48e3d668b7 ("VMware balloon: Enable notification via VMCI")
Cc: stable@vger.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If the hypervisor sets 2MB batching is on, while batching is cleared,
the balloon code breaks. In this case the legacy mechanism is used with
2MB page. The VM would report a 2MB page is ballooned, and the
hypervisor would only take the first 4KB.
While the hypervisor should not report such settings, make the code more
robust by not enabling 2MB support without batching.
Fixes: 365bd7ef7e ("VMware balloon: Support 2m page ballooning.")
Cc: stable@vger.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When balloon batching is not supported by the hypervisor, the guest
frame number (GFN) must fit in 32-bit. However, due to a bug, this check
was mistakenly ignored. In practice, when total RAM is greater than
16TB, the balloon does not work currently, making this bug unlikely to
happen.
Fixes: ef0f8f1129 ("VMware balloon: partially inline vmballoon_reserve_page.")
Cc: stable@vger.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
__GFP_WAIT was used to signal that the caller was in atomic context and
could not sleep. Now it is possible to distinguish between true atomic
context and callers that are not willing to sleep. The latter should
clear __GFP_DIRECT_RECLAIM so kswapd will still wake. As clearing
__GFP_WAIT behaves differently, there is a risk that people will clear the
wrong flags. This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly
indicate what it does -- setting it allows all reclaim activity, clearing
them prevents it.
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Get notified immediately when a balloon target is set, instead of waiting for
up to one second.
The up-to 1 second gap could be long enough to cause swapping inside of the
VM that receives the VM.
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Tested-by: Siva Sankar Reddy B <sankars@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Unify the behavior of the first start of the balloon and a reset. Also on
unload, declare that the balloon driver does not have any capabilities
anymore.
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2m ballooning significantly reduces the hypervisor side (and guest side)
overhead of ballooning and unballooning.
hypervisor only:
balloon unballoon
4 KB 2 GB/s 2.6 GB/s
2 MB 54 GB/s 767 GB/s
Use 2 MB pages as the hypervisor is alwys 64bit and 2 MB is the smallest
supported super-page size.
The code has to run on older versions of ESX and old balloon drivers run on
newer version of ESX. Hence match the capabilities with the host before 2m
page ballooning could be enabled.
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When VMware's hypervisor requests a VM to reclaim memory this is preferrably done
via ballooning. If the balloon driver does not return memory fast enough, more
drastic methods, such as hypervisor-level swapping are needed. These other methods
cause performance issues, e.g. hypervisor-level swapping requires the hypervisor to
swap in a page syncronously while the virtual CPU is blocked.
Hence it is in the interest of the VM to balloon memory as fast as possible. The
problem with doing this is that the VM might end up doing nothing else than
ballooning and the user might notice that the VM is stalled, esp. when the VM has
only a single virtual CPU.
This is less of a problem if the VM and the hypervisor perform balloon operations
faster. Also the balloon driver yields regularly, hence on a single virtual CPU
the Linux scheduler should be able to properly time-slice between ballooning and
other tasks.
Testing Done: quickly ballooned a lot of pages while wathing if there are any
perceived hickups (periods of non-responsiveness) in the execution of the
linux VM. No such hickups were seen.
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This helps with debugging vmw_balloon behavior, as it is clear what
functionality is enabled.
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of waiting for the next GET_TARGET command, we can react faster
by exploiting the fact that each hypervisor call also returns the
balloon target.
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Philip P. Moltmann <moltmann@vmware.com>
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Introduce a new capability to the driver that allow sending 512 pages in
one hypervisor call. This reduce the cost of the driver when reclaiming
memory.
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Philip P. Moltmann <moltmann@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In order to extend the balloon protocol, the hypervisor and the guest
driver need to agree on a set of supported functionality to use.
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Philip P. Moltmann <moltmann@vmware.com>
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This split the function in two: the allocation part is inlined into the
inflate function and the lock part is kept into his own function.
This change is needed in order to be able to allocate more than one page
before doing the hypervisor call.
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Philip P. Moltmann <moltmann@vmware.com>
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Based on a patch from: PaX Team <pageexec at freemail.hu> in a mailing
list message at:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120507/142707.html
Clang chokes on the notation "inl (%dx)" but works for "inl %dx"; GNU as accepts both forms.
CC: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fix for a -Wuninitialized compiler warning. Changed return value of
vmballoon_send_lock_page() from bool to int to be able to distinguish
between the error cases to avoid uninitialized use of hv_status in
vmballoon_reserve_page()
Signed-off-by: Danny Kukawka <danny.kukawka@bisect.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In vmballoon_reserve_page(), flags has been passed from the callee
function (vmballoon_inflate here). So, we can determine can_sleep outside
the loop.
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the arrival of concurrency-managed workqueues there is no need for
our driver to use dedicated workqueue; system-wide one should suffice just
fine.
[akpm@linux-foundation.org: fix comment layout & grammar]
Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are two spellings in use for 'freeze' + 'able' - 'freezable' and
'freezeable'. The former is the more prominent one. The latter is
mostly used by workqueue and in a few other odd places. Unify the
spelling to 'freezable'.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Steven Whitehouse <swhiteho@redhat.com>
When hypervisor decides to decrease target balloon size while the balloon
driver tries to lock pages hypervisor may respond with
VMW_BALLOON_PPN_NOTNEEDED. Use this data and immediately stop reserving
pages and wait for the next update cycle to fetch new target instead of
continuing trying to lock pages until size of refused list grows above
VMW_BALLOON_MAX_REFUSED (16) pages.
As a result the driver stops bothering the hypervisor with its attempts to
lock more pages that are not needed anymore. Most likely next order from
hypervisor will be to reduce ballon size anyway.
It is a small optimization.
Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In an effort to minimize customer confusion we want to unify naming
convention for VMware-provided kernel modules. This change renames the
balloon driver from vmware_ballon to vmw_balloon.
We expect to follow this naming convention (vmw_<module_name>) for all
modules that are part of mainline kernel and/or being distributed by
VMware, with the sole exception of vmxnet3 driver (since the name of
mainline driver happens to match with the name used in VMware Tools).
Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Acked-by: Bhavesh Davda <bhavesh@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>