Commit Graph

29 Commits

Author SHA1 Message Date
Alberto Garcia b5806108d2 throttle: Assert that bkt->max is valid in throttle_compute_wait()
If bkt->max == 0 and bkt->burst_length > 1 then we could have a
division by 0 in throttle_do_compute_wait(). That configuration is
however not permitted and is already detected by throttle_is_valid(),
but let's assert it in throttle_compute_wait() to make it explicit.

Found by Coverity (CID: 1381016).

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-09-26 14:46:23 +02:00
Manos Pitsidianakis 432d889e55 block: convert ThrottleGroup to object with QOM
ThrottleGroup is converted to an object. This will allow the future
throttle block filter drive easy creation and configuration of throttle
groups in QMP and cli.

A new QAPI struct, ThrottleLimits, is introduced to provide a shared
struct for all throttle configuration needs in QMP.

ThrottleGroups can be created via CLI as
    -object throttle-group,id=foo,x-iops-total=100,x-..
where x-* are individual limit properties. Since we can't add non-scalar
properties in -object this interface must be used instead. However,
setting these properties must be disabled after initialization because
certain combinations of limits are forbidden and thus configuration
changes should be done in one transaction. The individual properties
will go away when support for non-scalar values in CLI is implemented
and thus are marked as experimental.

ThrottleGroup also has a `limits` property that uses the ThrottleLimits
struct.  It can be used to create ThrottleGroups or set the
configuration in existing groups as follows:

{ "execute": "object-add",
  "arguments": {
    "qom-type": "throttle-group",
    "id": "foo",
    "props" : {
      "limits": {
          "iops-total": 100
      }
    }
  }
}
{ "execute" : "qom-set",
    "arguments" : {
        "path" : "foo",
        "property" : "limits",
        "value" : {
            "iops-total" : 99
        }
    }
}

This also means a group's configuration can be fetched with qom-get.

Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-09-05 18:12:21 +02:00
Alberto Garcia 67335a4558 throttle: Make burst_length 64bit and add range checks
LeakyBucket.burst_length is defined as an unsigned integer but the
code never checks for overflows and it only makes sure that the value
is not 0.

In practice this means that the user can set something like
throttling.iops-total-max-length=4294967300 despite being larger than
UINT_MAX and the final value after casting to unsigned int will be 4.

This patch changes the data type to uint64_t. This does not increase
the storage size of LeakyBucket, and allows us to assign the value
directly from qemu_opt_get_number() or BlockIOThrottle and then do the
checks directly in throttle_is_valid().

The value of burst_length does not have a specific upper limit,
but since the bucket size is defined by max * burst_length we have
to prevent overflows. Instead of going for UINT64_MAX or something
similar this patch reuses THROTTLE_VALUE_MAX, which allows I/O bursts
of 1 GiB/s for 10 days in a row.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 1b2e3049803f71cafb2e1fa1be4fb47147a0d398.1503580370.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-08-29 16:54:45 +01:00
Alberto Garcia d00e6923b1 throttle: Make LeakyBucket.avg and LeakyBucket.max integer types
Both the throttling limits set with the throttling.iops-* and
throttling.bps-* options and their QMP equivalents defined in the
BlockIOThrottle struct are integer values.

Those limits are also reported in the BlockDeviceInfo struct and they
are integers there as well.

Therefore there's no reason to store them internally as double and do
the conversion everytime we're setting or querying them, so this patch
uses uint64_t for those types. Let's also use an unsigned type because
we don't allow negative values anyway.

LeakyBucket.level and LeakyBucket.burst_level do however remain double
because their value changes depending on the fraction of time elapsed
since the previous I/O operation.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: f29b840422767b5be2c41c2dfdbbbf6c5f8fedf8.1503580370.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-08-29 16:54:45 +01:00
Alberto Garcia 2a8be39eba throttle: Remove throttle_fix_bucket() / throttle_unfix_bucket()
The throttling code can change internally the value of bkt->max if it
hasn't been set by the user. The problem with this is that if we want
to retrieve the original value we have to undo this change first. This
is ugly and unnecessary: this patch removes the throttle_fix_bucket()
and throttle_unfix_bucket() functions completely and moves the logic
to throttle_compute_wait().

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Message-id: 5b0b9e1ac6eb208d709eddc7b09e7669a523bff3.1503580370.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-08-29 16:54:45 +01:00
Alberto Garcia fa36f1b2eb throttle: Make throttle_is_valid() a bit less verbose
Use a pointer to the bucket instead of repeating cfg->buckets[i] all
the time. This makes the code more concise and will help us expand the
checks later and save a few line breaks.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 763ffc40a26b17d54cf93f5a999e4656049fcf0c.1503580370.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-08-29 16:54:45 +01:00
Alberto Garcia 0770a7a646 throttle: Update the throttle_fix_bucket() documentation
The way the throttling algorithm works is that requests start being
throttled once the bucket level exceeds the burst limit. When we get
there the bucket leaks at the level set by the user (bkt->avg), and
that leak rate is what prevents guest I/O from exceeding the desired
limit.

If we don't allow bursts (i.e. bkt->max == 0) then we can start
throttling requests immediately. The problem with keeping the
threshold at 0 is that it only allows one request at a time, and as
soon as there's a bit of I/O from the guest every other request will
be throttled and performance will suffer considerably. That can even
make the guest unable to reach the throttle limit if that limit is
high enough, and that happens regardless of the block scheduler used
by the guest.

Increasing that threshold gives flexibility to the guest, allowing it
to perform short bursts of I/O before being throttled. Increasing the
threshold too much does not make a difference in the long run (because
it's the leak rate what defines the actual throughput) but it does
allow the guest to perform longer initial bursts and exceed the
throttle limit for a short while.

A burst value of bkt->avg / 10 allows the guest to perform 100ms'
worth of I/O at the target rate without being throttled.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 31aae6645f0d1fbf3860fb2b528b757236f0c0a7.1503580370.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-08-29 16:54:44 +01:00
Manos Pitsidianakis 27e4cf1303 block: remove timer canceling in throttle_config()
throttle_config() cancels the timers of the calling BlockBackend. This
doesn't make sense because other BlockBackends in the group remain
untouched. There's no need to cancel the timers in the one specific
BlockBackend so let's not do that. Throttled requests will run as
scheduled and future requests will follow the new configuration. This
also allows a throttle group's configuration to be changed even when it
has no members.

Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-07-18 15:14:35 +02:00
Manos Pitsidianakis dbe824cc57 block: add clock_type field to ThrottleGroup
Clock type in throttling is currently inferred by the ThrottleTimer's
clock type even though it is a per-ThrottleGroup property; it doesn't
make sense to have different clock types in the same group. Moving this
to a field in ThrottleGroup can simplify some of the throttle functions.

Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-07-18 15:14:35 +02:00
Stefan Hajnoczi d72915c60b throttle: make throttle_config(throttle_get_config()) symmetric
Throttling has a weird property that throttle_get_config() does not
always return the same throttling settings that were given with
throttle_config().  In other words, the set and get functions aren't
symmetric.

If .max is 0 then the throttling code assigns a default value of .avg /
10 in throttle_config().  This is an implementation detail of the
throttling algorithm.  When throttle_get_config() is called the .max
value returned should still be 0.

Users are exposed to this quirk via "info block" or "query-block"
monitor commands.  This has caused confusion because it looks like a bug
when an unexpected value is reported.

This patch hides the .max value adjustment in throttle_get_config() and
updates test-throttle.c appropriately.

Reported-by: Nini Gu <ngu@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20170301115026.22621-4-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-04-21 10:36:12 +01:00
Alberto Garcia aaa1e77ffa throttle: Don't allow burst limits to be lower than the normal limits
Setting FOO_max to a value that is lower than FOO does not make
sense, and it produces odd results depending on the value of
FOO_max_length. Although the user should not set that configuration
in the first place it's better to reject it explicitly.

https://bugzilla.redhat.com/show_bug.cgi?id=1355665

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reported-by: Gu Nini <ngu@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 663d5aca406060e31f80d8113f77b6feee63b919.1469693110.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-08-05 09:59:06 +01:00
Stefan Hajnoczi 8860eabdee throttle: refuse iops-size without iops-total/read/write
In a similar vein to commit ee2bdc33c9
("throttle: refuse bps_max/iops_max without bps/iops") it is likely that
the user made a configuration error if iops-size has been set but no
iops limit has been set.

Print an error message so the user can check their throttling
configuration.  They should either remove iops-size if they don't want
any throttling or specify one of iops-total, iops-read, or iops-write.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1464828031-25601-1-git-send-email-stefanha@redhat.com
2016-06-07 14:40:51 +01:00
Markus Armbruster da34e65cb4 include/qemu/osdep.h: Don't include qapi/error.h
Commit 57cb38b included qapi/error.h into qemu/osdep.h to get the
Error typedef.  Since then, we've moved to include qemu/osdep.h
everywhere.  Its file comment explains: "To avoid getting into
possible circular include dependencies, this file should not include
any other QEMU headers, with the exceptions of config-host.h,
compiler.h, os-posix.h and os-win32.h, all of which are doing a
similar job to this file and are under similar constraints."
qapi/error.h doesn't do a similar job, and it doesn't adhere to
similar constraints: it includes qapi-types.h.  That's in excess of
100KiB of crap most .c files don't actually need.

Add the typedef to qemu/typedefs.h, and include that instead of
qapi/error.h.  Include qapi/error.h in .c files that need it and don't
get it now.  Include qapi-types.h in qom/object.h for uint16List.

Update scripts/clean-includes accordingly.  Update it further to match
reality: replace config.h by config-target.h, add sysemu/os-posix.h,
sysemu/os-win32.h.  Update the list of includes in the qemu/osdep.h
comment quoted above similarly.

This reduces the number of objects depending on qapi/error.h from "all
of them" to less than a third.  Unfortunately, the number depending on
qapi-types.h shrinks only a little.  More work is needed for that one.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
[Fix compilation without the spice devel packages. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-22 22:20:15 +01:00
Alberto Garcia 100f8f2608 throttle: Add support for burst periods
This patch adds support for burst periods to the throttling code.
With this feature the user can keep performing bursts as defined by
the LeakyBucket.max rate for a configurable period of time.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 14:08:05 +01:00
Alberto Garcia 1588ab5d0b throttle: Use throttle_config_init() to initialize ThrottleConfig
We can currently initialize ThrottleConfig by zeroing all its fields,
but this will change with the new fields to define the length of the
burst periods.

This patch introduces a new throttle_config_init() function and uses it
to replace all memset() calls that initialize ThrottleConfig directly.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 14:08:05 +01:00
Alberto Garcia d5851089a8 throttle: Merge all functions that check the configuration into one
There's no need to keep throttle_conflicting(), throttle_is_valid()
and throttle_max_is_missing_limit() as separate functions, so this
patch merges all three into one.

As a consequence, check_throttle_config() becomes redundant and can be
replaced with throttle_is_valid().

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 14:08:05 +01:00
Alberto Garcia 03ba36c83d throttle: Make throttle_is_valid() set errp
The caller does not need to set it, and this will allow us to refactor
this function later.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 14:08:04 +01:00
Alberto Garcia 45b2d418e0 throttle: Make throttle_max_is_missing_limit() set errp
The caller does not need to set it, and this will allow us to refactor
this function later.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 14:08:04 +01:00
Alberto Garcia 6921b18095 throttle: Make throttle_conflicting() set errp
The caller does not need to set it, and this will allow us to refactor
this function later.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 14:08:04 +01:00
Alberto Garcia 3c9242f5ae throttle: Make throttle_compute_timer() static
This function is only used internally in throttle.c

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-02-22 14:08:04 +01:00
Peter Maydell aafd758410 util: Clean up includes
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1454089805-5470-6-git-send-email-peter.maydell@linaro.org
2016-02-04 17:01:04 +00:00
Fam Zheng 972606c4db blockdev: Error out on negative throttling option values
extract_common_blockdev_options() uses qemu_opt_get_number() to parse
the bps/iops numbers to uint64_t, then converts to double and stores in
ThrottleConfig.  The actual parsing is done by strtoull() in
parse_option_number().  Negative numbers are wrapped to large positive
ones, and stored.

We used to reject negative numbers since 7d81c1413c, but this regressed
when the option parsing code was changed later. Now fix this again.

This time, define an arbitrary large upper limit (1e15),  and check the
values so both negative and impractically big numbers are caught and
reported.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-01-20 13:37:37 +01:00
Stefan Hajnoczi ee2bdc33c9 throttle: refuse bps_max/iops_max without bps/iops
The bps_max/iops_max values are meaningless without corresponding
bps/iops values.  Reported an error if bps_max/iops_max is given without
bps/iops.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1438683733-21111-2-git-send-email-stefanha@redhat.com
2015-08-05 12:53:48 +01:00
Stefan Hajnoczi 13566fe3e5 timer: rename NSEC_PER_SEC due to Mac OS X header clash
Commit e0cf11f31c ("timer: Use a single
definition of NSEC_PER_SEC for the whole codebase") renamed
NANOSECONDS_PER_SECOND to NSEC_PER_SEC.

On Mac OS X there is a <dispatch/time.h> system header which also
defines NSEC_PER_SEC.  This causes compiler warnings.

Let's use the old name instead.  It's longer but it doesn't clash.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1436364609-7929-1-git-send-email-stefanha@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2015-07-20 17:01:00 +01:00
Alberto Garcia e0cf11f31c timer: Use a single definition of NSEC_PER_SEC for the whole codebase
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: c6e55468856ba0b8f95913c4da111cc0ef266541.1434113783.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-07-02 09:20:18 +01:00
Alberto Garcia a291d5d9b9 throttle: Update throttle infrastructure copyright
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 07dcd4ed02f0110b13b3140f477b761b8bb8e270.1433779731.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-06-12 14:00:00 +01:00
Benoît Canet 0e5b0a2d54 throttle: Extract timers from ThrottleState into a separate structure
Group throttling will share ThrottleState between multiple bs.
As a consequence the ThrottleState will be accessed by multiple aio
context.

Timers are tied to their aio context so they must go out of the
ThrottleState structure.

This commit paves the way for each bs of a common ThrottleState to
have its own timer.

Signed-off-by: Benoit Canet <benoit.canet@nodalink.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 6cf9ea96d8b32ae2f8769cead38f68a6a0c8c909.1433779731.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-06-12 14:00:00 +01:00
Stefan Hajnoczi 13af91ebf0 throttle: add throttle_detach/attach_aio_context()
Block I/O throttling uses timers and currently always adds them to the
main loop.  Throttling will break if bdrv_set_aio_context() is used to
move a BlockDriverState to a different AioContext.

This patch adds throttle_detach/attach_aio_context() interfaces so the
throttling timers and uses them to move timers to the new AioContext.
Note that bdrv_set_aio_context() already drains all requests so we're
sure no throttled requests are pending.

The test cases need to be updated since the throttle_init() interface
has changed.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
2014-06-04 09:56:12 +02:00
Benoît Canet 5ddfffbdc5 throttle: Add a new throttling API implementing continuous leaky bucket.
Implement the continuous leaky bucket algorithm devised on IRC as a separate
module.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-09-06 15:25:07 +02:00