Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 637 insertions, 0 deletions

diff --git a/util/throttle.c b/util/throttle.c
new file mode 100644
index 000000000..81f247a8d
--- /dev/null
+++ b/util/throttle.c
@@ -0,0 +1,637 @@
+/*
+ * QEMU throttling infrastructure
+ *
+ * Copyright (C) Nodalink, EURL. 2013-2014
+ * Copyright (C) Igalia, S.L. 2015
+ *
+ * Authors:
+ *   Benoît Canet <benoit.canet@nodalink.com>
+ *   Alberto Garcia <berto@igalia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 or
+ * (at your option) version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/throttle.h"
+#include "qemu/timer.h"
+#include "block/aio.h"
+
+/* This function make a bucket leak
+ *
+ * @bkt:   the bucket to make leak
+ * @delta_ns: the time delta
+ */
+void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta_ns)
+{
+    double leak;
+
+    /* compute how much to leak */
+    leak = (bkt->avg * (double) delta_ns) / NANOSECONDS_PER_SECOND;
+
+    /* make the bucket leak */
+    bkt->level = MAX(bkt->level - leak, 0);
+
+    /* if we allow bursts for more than one second we also need to
+     * keep track of bkt->burst_level so the bkt->max goal per second
+     * is attained */
+    if (bkt->burst_length > 1) {
+        leak = (bkt->max * (double) delta_ns) / NANOSECONDS_PER_SECOND;
+        bkt->burst_level = MAX(bkt->burst_level - leak, 0);
+    }
+}
+
+/* Calculate the time delta since last leak and make proportionals leaks
+ *
+ * @now:      the current timestamp in ns
+ */
+static void throttle_do_leak(ThrottleState *ts, int64_t now)
+{
+    /* compute the time elapsed since the last leak */
+    int64_t delta_ns = now - ts->previous_leak;
+    int i;
+
+    ts->previous_leak = now;
+
+    if (delta_ns <= 0) {
+        return;
+    }
+
+    /* make each bucket leak */
+    for (i = 0; i < BUCKETS_COUNT; i++) {
+        throttle_leak_bucket(&ts->cfg.buckets[i], delta_ns);
+    }
+}
+
+/* do the real job of computing the time to wait
+ *
+ * @limit: the throttling limit
+ * @extra: the number of operation to delay
+ * @ret:   the time to wait in ns
+ */
+static int64_t throttle_do_compute_wait(double limit, double extra)
+{
+    double wait = extra * NANOSECONDS_PER_SECOND;
+    wait /= limit;
+    return wait;
+}
+
+/* This function compute the wait time in ns that a leaky bucket should trigger
+ *
+ * @bkt: the leaky bucket we operate on
+ * @ret: the resulting wait time in ns or 0 if the operation can go through
+ */
+int64_t throttle_compute_wait(LeakyBucket *bkt)
+{
+    double extra; /* the number of extra units blocking the io */
+    double bucket_size;   /* I/O before throttling to bkt->avg */
+    double burst_bucket_size; /* Before throttling to bkt->max */
+
+    if (!bkt->avg) {
+        return 0;
+    }
+
+    if (!bkt->max) {
+        /* If bkt->max is 0 we still want to allow short bursts of I/O
+         * from the guest, otherwise every other request will be throttled
+         * and performance will suffer considerably. */
+        bucket_size = (double) bkt->avg / 10;
+        burst_bucket_size = 0;
+    } else {
+        /* If we have a burst limit then we have to wait until all I/O
+         * at burst rate has finished before throttling to bkt->avg */
+        bucket_size = bkt->max * bkt->burst_length;
+        burst_bucket_size = (double) bkt->max / 10;
+    }
+
+    /* If the main bucket is full then we have to wait */
+    extra = bkt->level - bucket_size;
+    if (extra > 0) {
+        return throttle_do_compute_wait(bkt->avg, extra);
+    }
+
+    /* If the main bucket is not full yet we still have to check the
+     * burst bucket in order to enforce the burst limit */
+    if (bkt->burst_length > 1) {
+        assert(bkt->max > 0); /* see throttle_is_valid() */
+        extra = bkt->burst_level - burst_bucket_size;
+        if (extra > 0) {
+            return throttle_do_compute_wait(bkt->max, extra);
+        }
+    }
+
+    return 0;
+}
+
+/* This function compute the time that must be waited while this IO
+ *
+ * @is_write:   true if the current IO is a write, false if it's a read
+ * @ret:        time to wait
+ */
+static int64_t throttle_compute_wait_for(ThrottleState *ts,
+                                         bool is_write)
+{
+    BucketType to_check[2][4] = { {THROTTLE_BPS_TOTAL,
+                                   THROTTLE_OPS_TOTAL,
+                                   THROTTLE_BPS_READ,
+                                   THROTTLE_OPS_READ},
+                                  {THROTTLE_BPS_TOTAL,
+                                   THROTTLE_OPS_TOTAL,
+                                   THROTTLE_BPS_WRITE,
+                                   THROTTLE_OPS_WRITE}, };
+    int64_t wait, max_wait = 0;
+    int i;
+
+    for (i = 0; i < 4; i++) {
+        BucketType index = to_check[is_write][i];
+        wait = throttle_compute_wait(&ts->cfg.buckets[index]);
+        if (wait > max_wait) {
+            max_wait = wait;
+        }
+    }
+
+    return max_wait;
+}
+
+/* compute the timer for this type of operation
+ *
+ * @is_write:   the type of operation
+ * @now:        the current clock timestamp
+ * @next_timestamp: the resulting timer
+ * @ret:        true if a timer must be set
+ */
+static bool throttle_compute_timer(ThrottleState *ts,
+                                   bool is_write,
+                                   int64_t now,
+                                   int64_t *next_timestamp)
+{
+    int64_t wait;
+
+    /* leak proportionally to the time elapsed */
+    throttle_do_leak(ts, now);
+
+    /* compute the wait time if any */
+    wait = throttle_compute_wait_for(ts, is_write);
+
+    /* if the code must wait compute when the next timer should fire */
+    if (wait) {
+        *next_timestamp = now + wait;
+        return true;
+    }
+
+    /* else no need to wait at all */
+    *next_timestamp = now;
+    return false;
+}
+
+/* Add timers to event loop */
+void throttle_timers_attach_aio_context(ThrottleTimers *tt,
+                                        AioContext *new_context)
+{
+    tt->timers[0] = aio_timer_new(new_context, tt->clock_type, SCALE_NS,
+                                  tt->read_timer_cb, tt->timer_opaque);
+    tt->timers[1] = aio_timer_new(new_context, tt->clock_type, SCALE_NS,
+                                  tt->write_timer_cb, tt->timer_opaque);
+}
+
+/*
+ * Initialize the ThrottleConfig structure to a valid state
+ * @cfg: the config to initialize
+ */
+void throttle_config_init(ThrottleConfig *cfg)
+{
+    unsigned i;
+    memset(cfg, 0, sizeof(*cfg));
+    for (i = 0; i < BUCKETS_COUNT; i++) {
+        cfg->buckets[i].burst_length = 1;
+    }
+}
+
+/* To be called first on the ThrottleState */
+void throttle_init(ThrottleState *ts)
+{
+    memset(ts, 0, sizeof(ThrottleState));
+    throttle_config_init(&ts->cfg);
+}
+
+/* To be called first on the ThrottleTimers */
+void throttle_timers_init(ThrottleTimers *tt,
+                          AioContext *aio_context,
+                          QEMUClockType clock_type,
+                          QEMUTimerCB *read_timer_cb,
+                          QEMUTimerCB *write_timer_cb,
+                          void *timer_opaque)
+{
+    memset(tt, 0, sizeof(ThrottleTimers));
+
+    tt->clock_type = clock_type;
+    tt->read_timer_cb = read_timer_cb;
+    tt->write_timer_cb = write_timer_cb;
+    tt->timer_opaque = timer_opaque;
+    throttle_timers_attach_aio_context(tt, aio_context);
+}
+
+/* destroy a timer */
+static void throttle_timer_destroy(QEMUTimer **timer)
+{
+    assert(*timer != NULL);
+
+    timer_free(*timer);
+    *timer = NULL;
+}
+
+/* Remove timers from event loop */
+void throttle_timers_detach_aio_context(ThrottleTimers *tt)
+{
+    int i;
+
+    for (i = 0; i < 2; i++) {
+        throttle_timer_destroy(&tt->timers[i]);
+    }
+}
+
+/* To be called last on the ThrottleTimers */
+void throttle_timers_destroy(ThrottleTimers *tt)
+{
+    throttle_timers_detach_aio_context(tt);
+}
+
+/* is any throttling timer configured */
+bool throttle_timers_are_initialized(ThrottleTimers *tt)
+{
+    if (tt->timers[0]) {
+        return true;
+    }
+
+    return false;
+}
+
+/* Does any throttling must be done
+ *
+ * @cfg: the throttling configuration to inspect
+ * @ret: true if throttling must be done else false
+ */
+bool throttle_enabled(ThrottleConfig *cfg)
+{
+    int i;
+
+    for (i = 0; i < BUCKETS_COUNT; i++) {
+        if (cfg->buckets[i].avg > 0) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+/* check if a throttling configuration is valid
+ * @cfg: the throttling configuration to inspect
+ * @ret: true if valid else false
+ * @errp: error object
+ */
+bool throttle_is_valid(ThrottleConfig *cfg, Error **errp)
+{
+    int i;
+    bool bps_flag, ops_flag;
+    bool bps_max_flag, ops_max_flag;
+
+    bps_flag = cfg->buckets[THROTTLE_BPS_TOTAL].avg &&
+               (cfg->buckets[THROTTLE_BPS_READ].avg ||
+                cfg->buckets[THROTTLE_BPS_WRITE].avg);
+
+    ops_flag = cfg->buckets[THROTTLE_OPS_TOTAL].avg &&
+               (cfg->buckets[THROTTLE_OPS_READ].avg ||
+                cfg->buckets[THROTTLE_OPS_WRITE].avg);
+
+    bps_max_flag = cfg->buckets[THROTTLE_BPS_TOTAL].max &&
+                  (cfg->buckets[THROTTLE_BPS_READ].max  ||
+                   cfg->buckets[THROTTLE_BPS_WRITE].max);
+
+    ops_max_flag = cfg->buckets[THROTTLE_OPS_TOTAL].max &&
+                   (cfg->buckets[THROTTLE_OPS_READ].max ||
+                   cfg->buckets[THROTTLE_OPS_WRITE].max);
+
+    if (bps_flag || ops_flag || bps_max_flag || ops_max_flag) {
+        error_setg(errp, "bps/iops/max total values and read/write values"
+                   " cannot be used at the same time");
+        return false;
+    }
+
+    if (cfg->op_size &&
+        !cfg->buckets[THROTTLE_OPS_TOTAL].avg &&
+        !cfg->buckets[THROTTLE_OPS_READ].avg &&
+        !cfg->buckets[THROTTLE_OPS_WRITE].avg) {
+        error_setg(errp, "iops size requires an iops value to be set");
+        return false;
+    }
+
+    for (i = 0; i < BUCKETS_COUNT; i++) {
+        LeakyBucket *bkt = &cfg->buckets[i];
+        if (bkt->avg > THROTTLE_VALUE_MAX || bkt->max > THROTTLE_VALUE_MAX) {
+            error_setg(errp, "bps/iops/max values must be within [0, %lld]",
+                       THROTTLE_VALUE_MAX);
+            return false;
+        }
+
+        if (!bkt->burst_length) {
+            error_setg(errp, "the burst length cannot be 0");
+            return false;
+        }
+
+        if (bkt->burst_length > 1 && !bkt->max) {
+            error_setg(errp, "burst length set without burst rate");
+            return false;
+        }
+
+        if (bkt->max && bkt->burst_length > THROTTLE_VALUE_MAX / bkt->max) {
+            error_setg(errp, "burst length too high for this burst rate");
+            return false;
+        }
+
+        if (bkt->max && !bkt->avg) {
+            error_setg(errp, "bps_max/iops_max require corresponding"
+                       " bps/iops values");
+            return false;
+        }
+
+        if (bkt->max && bkt->max < bkt->avg) {
+            error_setg(errp, "bps_max/iops_max cannot be lower than bps/iops");
+            return false;
+        }
+    }
+
+    return true;
+}
+
+/* Used to configure the throttle
+ *
+ * @ts: the throttle state we are working on
+ * @clock_type: the group's clock_type
+ * @cfg: the config to set
+ */
+void throttle_config(ThrottleState *ts,
+                     QEMUClockType clock_type,
+                     ThrottleConfig *cfg)
+{
+    int i;
+
+    ts->cfg = *cfg;
+
+    /* Zero bucket level */
+    for (i = 0; i < BUCKETS_COUNT; i++) {
+        ts->cfg.buckets[i].level = 0;
+        ts->cfg.buckets[i].burst_level = 0;
+    }
+
+    ts->previous_leak = qemu_clock_get_ns(clock_type);
+}
+
+/* used to get config
+ *
+ * @ts:  the throttle state we are working on
+ * @cfg: the config to write
+ */
+void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg)
+{
+    *cfg = ts->cfg;
+}
+
+
+/* Schedule the read or write timer if needed
+ *
+ * NOTE: this function is not unit tested due to it's usage of timer_mod
+ *
+ * @tt:       the timers structure
+ * @is_write: the type of operation (read/write)
+ * @ret:      true if the timer has been scheduled else false
+ */
+bool throttle_schedule_timer(ThrottleState *ts,
+                             ThrottleTimers *tt,
+                             bool is_write)
+{
+    int64_t now = qemu_clock_get_ns(tt->clock_type);
+    int64_t next_timestamp;
+    bool must_wait;
+
+    must_wait = throttle_compute_timer(ts,
+                                       is_write,
+                                       now,
+                                       &next_timestamp);
+
+    /* request not throttled */
+    if (!must_wait) {
+        return false;
+    }
+
+    /* request throttled and timer pending -> do nothing */
+    if (timer_pending(tt->timers[is_write])) {
+        return true;
+    }
+
+    /* request throttled and timer not pending -> arm timer */
+    timer_mod(tt->timers[is_write], next_timestamp);
+    return true;
+}
+
+/* do the accounting for this operation
+ *
+ * @is_write: the type of operation (read/write)
+ * @size:     the size of the operation
+ */
+void throttle_account(ThrottleState *ts, bool is_write, uint64_t size)
+{
+    const BucketType bucket_types_size[2][2] = {
+        { THROTTLE_BPS_TOTAL, THROTTLE_BPS_READ },
+        { THROTTLE_BPS_TOTAL, THROTTLE_BPS_WRITE }
+    };
+    const BucketType bucket_types_units[2][2] = {
+        { THROTTLE_OPS_TOTAL, THROTTLE_OPS_READ },
+        { THROTTLE_OPS_TOTAL, THROTTLE_OPS_WRITE }
+    };
+    double units = 1.0;
+    unsigned i;
+
+    /* if cfg.op_size is defined and smaller than size we compute unit count */
+    if (ts->cfg.op_size && size > ts->cfg.op_size) {
+        units = (double) size / ts->cfg.op_size;
+    }
+
+    for (i = 0; i < 2; i++) {
+        LeakyBucket *bkt;
+
+        bkt = &ts->cfg.buckets[bucket_types_size[is_write][i]];
+        bkt->level += size;
+        if (bkt->burst_length > 1) {
+            bkt->burst_level += size;
+        }
+
+        bkt = &ts->cfg.buckets[bucket_types_units[is_write][i]];
+        bkt->level += units;
+        if (bkt->burst_length > 1) {
+            bkt->burst_level += units;
+        }
+    }
+}
+
+/* return a ThrottleConfig based on the options in a ThrottleLimits
+ *
+ * @arg:    the ThrottleLimits object to read from
+ * @cfg:    the ThrottleConfig to edit
+ * @errp:   error object
+ */
+void throttle_limits_to_config(ThrottleLimits *arg, ThrottleConfig *cfg,
+                               Error **errp)
+{
+    if (arg->has_bps_total) {
+        cfg->buckets[THROTTLE_BPS_TOTAL].avg = arg->bps_total;
+    }
+    if (arg->has_bps_read) {
+        cfg->buckets[THROTTLE_BPS_READ].avg  = arg->bps_read;
+    }
+    if (arg->has_bps_write) {
+        cfg->buckets[THROTTLE_BPS_WRITE].avg = arg->bps_write;
+    }
+
+    if (arg->has_iops_total) {
+        cfg->buckets[THROTTLE_OPS_TOTAL].avg = arg->iops_total;
+    }
+    if (arg->has_iops_read) {
+        cfg->buckets[THROTTLE_OPS_READ].avg  = arg->iops_read;
+    }
+    if (arg->has_iops_write) {
+        cfg->buckets[THROTTLE_OPS_WRITE].avg = arg->iops_write;
+    }
+
+    if (arg->has_bps_total_max) {
+        cfg->buckets[THROTTLE_BPS_TOTAL].max = arg->bps_total_max;
+    }
+    if (arg->has_bps_read_max) {
+        cfg->buckets[THROTTLE_BPS_READ].max = arg->bps_read_max;
+    }
+    if (arg->has_bps_write_max) {
+        cfg->buckets[THROTTLE_BPS_WRITE].max = arg->bps_write_max;
+    }
+    if (arg->has_iops_total_max) {
+        cfg->buckets[THROTTLE_OPS_TOTAL].max = arg->iops_total_max;
+    }
+    if (arg->has_iops_read_max) {
+        cfg->buckets[THROTTLE_OPS_READ].max = arg->iops_read_max;
+    }
+    if (arg->has_iops_write_max) {
+        cfg->buckets[THROTTLE_OPS_WRITE].max = arg->iops_write_max;
+    }
+
+    if (arg->has_bps_total_max_length) {
+        if (arg->bps_total_max_length > UINT_MAX) {
+            error_setg(errp, "bps-total-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_BPS_TOTAL].burst_length = arg->bps_total_max_length;
+    }
+    if (arg->has_bps_read_max_length) {
+        if (arg->bps_read_max_length > UINT_MAX) {
+            error_setg(errp, "bps-read-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_BPS_READ].burst_length = arg->bps_read_max_length;
+    }
+    if (arg->has_bps_write_max_length) {
+        if (arg->bps_write_max_length > UINT_MAX) {
+            error_setg(errp, "bps-write-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_BPS_WRITE].burst_length = arg->bps_write_max_length;
+    }
+    if (arg->has_iops_total_max_length) {
+        if (arg->iops_total_max_length > UINT_MAX) {
+            error_setg(errp, "iops-total-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_OPS_TOTAL].burst_length = arg->iops_total_max_length;
+    }
+    if (arg->has_iops_read_max_length) {
+        if (arg->iops_read_max_length > UINT_MAX) {
+            error_setg(errp, "iops-read-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_OPS_READ].burst_length = arg->iops_read_max_length;
+    }
+    if (arg->has_iops_write_max_length) {
+        if (arg->iops_write_max_length > UINT_MAX) {
+            error_setg(errp, "iops-write-max-length value must be in"
+                             " the range [0, %u]", UINT_MAX);
+            return;
+        }
+        cfg->buckets[THROTTLE_OPS_WRITE].burst_length = arg->iops_write_max_length;
+    }
+
+    if (arg->has_iops_size) {
+        cfg->op_size = arg->iops_size;
+    }
+
+    throttle_is_valid(cfg, errp);
+}
+
+/* write the options of a ThrottleConfig to a ThrottleLimits
+ *
+ * @cfg:    the ThrottleConfig to read from
+ * @var:    the ThrottleLimits to write to
+ */
+void throttle_config_to_limits(ThrottleConfig *cfg, ThrottleLimits *var)
+{
+    var->bps_total               = cfg->buckets[THROTTLE_BPS_TOTAL].avg;
+    var->bps_read                = cfg->buckets[THROTTLE_BPS_READ].avg;
+    var->bps_write               = cfg->buckets[THROTTLE_BPS_WRITE].avg;
+    var->iops_total              = cfg->buckets[THROTTLE_OPS_TOTAL].avg;
+    var->iops_read               = cfg->buckets[THROTTLE_OPS_READ].avg;
+    var->iops_write              = cfg->buckets[THROTTLE_OPS_WRITE].avg;
+    var->bps_total_max           = cfg->buckets[THROTTLE_BPS_TOTAL].max;
+    var->bps_read_max            = cfg->buckets[THROTTLE_BPS_READ].max;
+    var->bps_write_max           = cfg->buckets[THROTTLE_BPS_WRITE].max;
+    var->iops_total_max          = cfg->buckets[THROTTLE_OPS_TOTAL].max;
+    var->iops_read_max           = cfg->buckets[THROTTLE_OPS_READ].max;
+    var->iops_write_max          = cfg->buckets[THROTTLE_OPS_WRITE].max;
+    var->bps_total_max_length    = cfg->buckets[THROTTLE_BPS_TOTAL].burst_length;
+    var->bps_read_max_length     = cfg->buckets[THROTTLE_BPS_READ].burst_length;
+    var->bps_write_max_length    = cfg->buckets[THROTTLE_BPS_WRITE].burst_length;
+    var->iops_total_max_length   = cfg->buckets[THROTTLE_OPS_TOTAL].burst_length;
+    var->iops_read_max_length    = cfg->buckets[THROTTLE_OPS_READ].burst_length;
+    var->iops_write_max_length   = cfg->buckets[THROTTLE_OPS_WRITE].burst_length;
+    var->iops_size               = cfg->op_size;
+
+    var->has_bps_total = true;
+    var->has_bps_read = true;
+    var->has_bps_write = true;
+    var->has_iops_total = true;
+    var->has_iops_read = true;
+    var->has_iops_write = true;
+    var->has_bps_total_max = true;
+    var->has_bps_read_max = true;
+    var->has_bps_write_max = true;
+    var->has_iops_total_max = true;
+    var->has_iops_read_max = true;
+    var->has_iops_write_max = true;
+    var->has_bps_read_max_length = true;
+    var->has_bps_total_max_length = true;
+    var->has_bps_write_max_length = true;
+    var->has_iops_total_max_length = true;
+    var->has_iops_read_max_length = true;
+    var->has_iops_write_max_length = true;
+    var->has_iops_size = true;
+}