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libvirt/src/util/virnetdevbandwidth.c
Michal Privoznik 065054daa7 virnetdevbandwidth: Compute quantum value 
I've noticed couple of warning in dmesg while debugging
something:

[ 9683.973754] HTB: quantum of class 10001 is big. Consider r2q change.
[ 9683.976460] HTB: quantum of class 10002 is big. Consider r2q change.

I've read the HTB documentation and linux kernel code to find out
what's wrong. Basically we need to pass another argument
"quantum" to our tc cmd line because the default computed by HTB
does not always work in which case the warning message is printed
out.

You can read more details here:

http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm#sharing

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2016-02-05 16:43:19 +01:00

753 lines
24 KiB
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/*
* Copyright (C) 2009-2015 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
* Authors:
* Michal Privoznik <mprivozn@redhat.com>
* Daniel P. Berrange <berrange@redhat.com>
*/
#include <config.h>
#include <unistd.h>
#include "virnetdevbandwidth.h"
#include "vircommand.h"
#include "viralloc.h"
#include "virerror.h"
#include "virstring.h"
#include "virutil.h"
#define VIR_FROM_THIS VIR_FROM_NONE
void
virNetDevBandwidthFree(virNetDevBandwidthPtr def)
{
if (!def)
return;
VIR_FREE(def->in);
VIR_FREE(def->out);
VIR_FREE(def);
}
static void
virNetDevBandwidthCmdAddOptimalQuantum(virCommandPtr cmd,
const virNetDevBandwidthRate *rate)
{
const unsigned long long mtu = 1500;
unsigned long long r2q;
/* When two or more classes compete for unused bandwidth they are each
* given some number of bytes before serving other competing class. This
* number is called quantum. It's advised in HTB docs that the number
* should be equal to MTU. The class quantum is computed from its rate
* divided by global r2q parameter. However, if rate is too small the
* default value will not suffice and thus we must provide our own value.
* */
r2q = rate->average * 1024 / 8 / mtu;
if (!r2q)
r2q = 1;
virCommandAddArg(cmd, "quantum");
virCommandAddArgFormat(cmd, "%llu", r2q);
}
/**
* virNetDevBandwidthManipulateFilter:
* @ifname: interface to operate on
* @ifmac_ptr: MAC of the interface to create filter over
* @id: filter ID
* @class_id: where to place traffic
* @remove_old: whether to remove the filter
* @create_new: whether to create the filter
*
* TC filters are as crucial for traffic shaping as QDiscs. While
* QDiscs act like black boxes deciding which packets should be
* held up and which should be sent immediately, it's the filter
* that places a packet into the box. So, we may end up
* constructing a set of filters on a single device (e.g. a
* bridge) and filter the traffic into QDiscs based on the
* originating vNET device.
*
* Long story short, @ifname is the interface where the filter
* should be created. The @ifmac_ptr is the MAC address for which
* the filter should be created (usually different to the MAC
* address of @ifname). Then, like everything - even filters have
* an @id which should be unique (per @ifname). And @class_id
* tells into which QDisc should filter place the traffic.
*
* This function can be used for both, removing stale filter
* (@remove_old set to true) and creating new one (@create_new
* set to true). Both at once for the same price!
*
* Returns: 0 on success,
* -1 otherwise (with error reported).
*/
static int ATTRIBUTE_NONNULL(1)
virNetDevBandwidthManipulateFilter(const char *ifname,
const virMacAddr *ifmac_ptr,
unsigned int id,
const char *class_id,
bool remove_old,
bool create_new)
{
int ret = -1;
char *filter_id = NULL;
virCommandPtr cmd = NULL;
unsigned char ifmac[VIR_MAC_BUFLEN];
char *mac[2] = {NULL, NULL};
if (!(remove_old || create_new)) {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("filter creation API error"));
goto cleanup;
}
/* u32 filters must have 800:: prefix. Don't ask. */
if (virAsprintf(&filter_id, "800::%u", id) < 0)
goto cleanup;
if (remove_old) {
int cmd_ret = 0;
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "filter", "del", "dev", ifname,
"prio", "2", "handle", filter_id, "u32", NULL);
if (virCommandRun(cmd, &cmd_ret) < 0)
goto cleanup;
}
if (create_new) {
virMacAddrGetRaw(ifmac_ptr, ifmac);
if (virAsprintf(&mac[0], "0x%02x%02x%02x%02x", ifmac[2],
ifmac[3], ifmac[4], ifmac[5]) < 0 ||
virAsprintf(&mac[1], "0x%02x%02x", ifmac[0], ifmac[1]) < 0)
goto cleanup;
virCommandFree(cmd);
cmd = virCommandNew(TC);
/* Okay, this not nice. But since libvirt does not necessarily track
* interface IP address(es), and tc fw filter simply refuse to use
* ebtables marks, we need to use u32 selector to match MAC address.
* If libvirt will ever know something, remove this FIXME
*/
virCommandAddArgList(cmd, "filter", "add", "dev", ifname, "protocol", "ip",
"prio", "2", "handle", filter_id, "u32",
"match", "u16", "0x0800", "0xffff", "at", "-2",
"match", "u32", mac[0], "0xffffffff", "at", "-12",
"match", "u16", mac[1], "0xffff", "at", "-14",
"flowid", class_id, NULL);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
}
ret = 0;
cleanup:
VIR_FREE(mac[1]);
VIR_FREE(mac[0]);
VIR_FREE(filter_id);
virCommandFree(cmd);
return ret;
}
/**
* virNetDevBandwidthSet:
* @ifname: on which interface
* @bandwidth: rates to set (may be NULL)
* @hierarchical_class: whether to create hierarchical class
*
* This function enables QoS on specified interface
* and set given traffic limits for both, incoming
* and outgoing traffic. Any previous setting get
* overwritten. If @hierarchical_class is TRUE, create
* hierarchical class. It is used to guarantee minimal
* throughput ('floor' attribute in NIC).
*
* Return 0 on success, -1 otherwise.
*/
int
virNetDevBandwidthSet(const char *ifname,
virNetDevBandwidthPtr bandwidth,
bool hierarchical_class)
{
int ret = -1;
virCommandPtr cmd = NULL;
char *average = NULL;
char *peak = NULL;
char *burst = NULL;
if (!bandwidth) {
/* nothing to be enabled */
ret = 0;
goto cleanup;
}
if (geteuid() != 0) {
virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
_("Network bandwidth tuning is not available"
" in session mode"));
return -1;
}
if (!ifname) {
virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
_("Unable to set bandwidth for interface because "
"device name is unknown"));
return -1;
}
virNetDevBandwidthClear(ifname);
if (bandwidth->in && bandwidth->in->average) {
if (virAsprintf(&average, "%llukbps", bandwidth->in->average) < 0)
goto cleanup;
if (bandwidth->in->peak &&
(virAsprintf(&peak, "%llukbps", bandwidth->in->peak) < 0))
goto cleanup;
if (bandwidth->in->burst &&
(virAsprintf(&burst, "%llukb", bandwidth->in->burst) < 0))
goto cleanup;
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "qdisc", "add", "dev", ifname, "root",
"handle", "1:", "htb", "default",
hierarchical_class ? "2" : "1", NULL);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
/* If we are creating a hierarchical class, all non guaranteed traffic
* goes to the 1:2 class which will adjust 'rate' dynamically as NICs
* with guaranteed throughput are plugged and unplugged. Class 1:1
* exists so we don't exceed the maximum limit for the network. For each
* NIC with guaranteed throughput a separate classid will be created.
* NB '1:' is just a shorter notation of '1:0'.
*
* To get a picture how this works:
*
* +-----+ +---------+ +-----------+ +-----------+ +-----+
* | | | qdisc | | class 1:1 | | class 1:2 | | |
* | NIC | | def 1:2 | | rate | | rate | | sfq |
* | | --> | | --> | peak | -+-> | peak | --> | |
* +-----+ +---------+ +-----------+ | +-----------+ +-----+
* |
* | +-----------+ +-----+
* | | class 1:3 | | |
* | | rate | | sfq |
* +-> | peak | --> | |
* | +-----------+ +-----+
* ...
* | +-----------+ +-----+
* | | class 1:n | | |
* | | rate | | sfq |
* +-> | peak | --> | |
* +-----------+ +-----+
*
* After the routing decision, when is it clear a packet is to be sent
* via a particular NIC, it is sent to the root qdisc (queueing
* discipline). In this case HTB (Hierarchical Token Bucket). It has
* only one direct child class (with id 1:1) which shapes the overall
* rate that is sent through the NIC. This class has at least one child
* (1:2) which is meant for all non-privileged (non guaranteed) traffic
* from all domains. Then, for each interface with guaranteed
* throughput, a separate class (1:n) is created. Imagine a class is a
* box. Whenever a packet ends up in a class it is stored in this box
* until the kernel sends it, then it is removed from box. Packets are
* placed into boxes based on rules (filters) - e.g. depending on
* destination IP/MAC address. If there is no rule to be applied, the
* root qdisc has a default where such packets go (1:2 in this case).
* Packets come in over and over again and boxes get filled more and
* more. Imagine that kernel sends packets just once a second. So it
* starts to traverse through this tree. It starts with the root qdisc
* and through 1:1 it gets to 1:2. It sends packets up to 1:2's 'rate'.
* Then it moves to 1:3 and again sends packets up to 1:3's 'rate'. The
* whole process is repeated until 1:n is processed. So now we have
* ensured each class its guaranteed bandwidth. If the sum of sent data
* doesn't exceed the 'rate' in 1:1 class, we can go further and send
* more packets. The rest of available bandwidth is distributed to the
* 1:2,1:3...1:n classes by ratio of their 'rate'. As soon as the root
* 'rate' limit is reached or there are no more packets to send, we stop
* sending and wait another second. Each class has an SFQ qdisc which
* shuffles packets in boxes stochastically, so one sender cannot
* starve others.
*
* Therefore, whenever we want to plug in a new guaranteed interface, we
* need to create a new class and adjust the 'rate' of the 1:2 class.
* When unplugging we do the exact opposite - remove the associated
* class, and adjust the 'rate'.
*
* This description is rather long, but it is still a good idea to read
* it before you dig into the code.
*/
if (hierarchical_class) {
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "class", "add", "dev", ifname, "parent",
"1:", "classid", "1:1", "htb", "rate", average,
"ceil", peak ? peak : average, NULL);
virNetDevBandwidthCmdAddOptimalQuantum(cmd, bandwidth->in);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
}
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "class", "add", "dev", ifname, "parent",
hierarchical_class ? "1:1" : "1:", "classid",
hierarchical_class ? "1:2" : "1:1", "htb",
"rate", average, NULL);
if (peak)
virCommandAddArgList(cmd, "ceil", peak, NULL);
if (burst)
virCommandAddArgList(cmd, "burst", burst, NULL);
virNetDevBandwidthCmdAddOptimalQuantum(cmd, bandwidth->in);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "qdisc", "add", "dev", ifname, "parent",
hierarchical_class ? "1:2" : "1:1",
"handle", "2:", "sfq", "perturb",
"10", NULL);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "filter", "add", "dev", ifname, "parent",
"1:0", "protocol", "all", "prio", "1", "handle",
"1", "fw", "flowid", "1", NULL);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
VIR_FREE(average);
VIR_FREE(peak);
VIR_FREE(burst);
}
if (bandwidth->out) {
if (virAsprintf(&average, "%llukbps", bandwidth->out->average) < 0)
goto cleanup;
if (virAsprintf(&burst, "%llukb", bandwidth->out->burst ?
bandwidth->out->burst : bandwidth->out->average) < 0)
goto cleanup;
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "qdisc", "add", "dev", ifname,
"ingress", NULL);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
virCommandFree(cmd);
cmd = virCommandNew(TC);
/* Set filter to match all ingress traffic */
virCommandAddArgList(cmd, "filter", "add", "dev", ifname, "parent",
"ffff:", "protocol", "all", "u32", "match", "u32",
"0", "0", "police", "rate", average,
"burst", burst, "mtu", "64kb", "drop", "flowid",
":1", NULL);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
}
ret = 0;
cleanup:
virCommandFree(cmd);
VIR_FREE(average);
VIR_FREE(peak);
VIR_FREE(burst);
return ret;
}
/**
* virNetDevBandwidthClear:
* @ifname: on which interface
*
* This function tries to disable QoS on specified interface
* by deleting root and ingress qdisc. However, this may fail
* if we try to remove the default one.
*
* Return 0 on success, -1 otherwise.
*/
int
virNetDevBandwidthClear(const char *ifname)
{
int ret = 0;
int dummy; /* for ignoring the exit status */
virCommandPtr cmd = NULL;
if (!ifname)
return 0;
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "qdisc", "del", "dev", ifname, "root", NULL);
if (virCommandRun(cmd, &dummy) < 0)
ret = -1;
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "qdisc", "del", "dev", ifname, "ingress", NULL);
if (virCommandRun(cmd, &dummy) < 0)
ret = -1;
virCommandFree(cmd);
return ret;
}
/*
* virNetDevBandwidthCopy:
* @dest: destination
* @src: source (may be NULL)
*
* Returns -1 on OOM error (which gets reported),
* 0 otherwise.
*/
int
virNetDevBandwidthCopy(virNetDevBandwidthPtr *dest,
const virNetDevBandwidth *src)
{
int ret = -1;
*dest = NULL;
if (!src) {
/* nothing to be copied */
return 0;
}
if (VIR_ALLOC(*dest) < 0)
goto cleanup;
if (src->in) {
if (VIR_ALLOC((*dest)->in) < 0)
goto cleanup;
memcpy((*dest)->in, src->in, sizeof(*src->in));
}
if (src->out) {
if (VIR_ALLOC((*dest)->out) < 0) {
VIR_FREE((*dest)->in);
goto cleanup;
}
memcpy((*dest)->out, src->out, sizeof(*src->out));
}
ret = 0;
cleanup:
if (ret < 0) {
virNetDevBandwidthFree(*dest);
*dest = NULL;
}
return ret;
}
bool
virNetDevBandwidthEqual(virNetDevBandwidthPtr a,
virNetDevBandwidthPtr b)
{
if (!a && !b)
return true;
if (!a || !b)
return false;
/* in */
if (a->in) {
if (!b->in)
return false;
if (a->in->average != b->in->average ||
a->in->peak != b->in->peak ||
a->in->floor != b->in->floor ||
a->in->burst != b->in->burst)
return false;
} else if (b->in) {
return false;
}
/*out*/
if (a->out) {
if (!b->out)
return false;
if (a->out->average != b->out->average ||
a->out->peak != b->out->peak ||
a->out->floor != b->out->floor ||
a->out->burst != b->out->burst)
return false;
} else if (b->out) {
return false;
}
return true;
}
/*
* virNetDevBandwidthPlug:
* @brname: name of the bridge
* @net_bandwidth: QoS settings on @brname
* @ifmac_ptr: MAC of interface
* @bandwidth: QoS settings for interface
* @id: unique ID (MUST be greater than 2)
*
* Set bridge part of interface QoS settings, e.g. guaranteed
* bandwidth. @id is an unique ID (among @brname) from which
* other identifiers for class, qdisc and filter are derived.
* However, two classes were already set up (by
* virNetDevBandwidthSet). That's why this @id MUST be greater
* than 2. You may want to keep passed @id, as it is used later
* by virNetDevBandwidthUnplug.
*
* Returns:
* 0 if QoS set successfully
* -1 otherwise.
*/
int
virNetDevBandwidthPlug(const char *brname,
virNetDevBandwidthPtr net_bandwidth,
const virMacAddr *ifmac_ptr,
virNetDevBandwidthPtr bandwidth,
unsigned int id)
{
int ret = -1;
virCommandPtr cmd = NULL;
char *class_id = NULL;
char *qdisc_id = NULL;
char *floor = NULL;
char *ceil = NULL;
char ifmacStr[VIR_MAC_STRING_BUFLEN];
if (id <= 2) {
virReportError(VIR_ERR_INTERNAL_ERROR, _("Invalid class ID %d"), id);
return -1;
}
virMacAddrFormat(ifmac_ptr, ifmacStr);
if (!net_bandwidth || !net_bandwidth->in) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
_("Bridge '%s' has no QoS set, therefore "
"unable to set 'floor' on '%s'"),
brname, ifmacStr);
return -1;
}
if (virAsprintf(&class_id, "1:%x", id) < 0 ||
virAsprintf(&qdisc_id, "%x:", id) < 0 ||
virAsprintf(&floor, "%llukbps", bandwidth->in->floor) < 0 ||
virAsprintf(&ceil, "%llukbps", net_bandwidth->in->peak ?
net_bandwidth->in->peak :
net_bandwidth->in->average) < 0)
goto cleanup;
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "class", "add", "dev", brname, "parent", "1:1",
"classid", class_id, "htb", "rate", floor,
"ceil", ceil, NULL);
virNetDevBandwidthCmdAddOptimalQuantum(cmd, bandwidth->in);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "qdisc", "add", "dev", brname, "parent",
class_id, "handle", qdisc_id, "sfq", "perturb",
"10", NULL);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
if (virNetDevBandwidthManipulateFilter(brname, ifmac_ptr, id,
class_id, false, true) < 0)
goto cleanup;
ret = 0;
cleanup:
VIR_FREE(ceil);
VIR_FREE(floor);
VIR_FREE(qdisc_id);
VIR_FREE(class_id);
virCommandFree(cmd);
return ret;
}
/*
* virNetDevBandwidthUnplug:
* @brname: from which bridge are we unplugging
* @id: unique identifier (MUST be greater than 2)
*
* Remove QoS settings from bridge.
*
* Returns 0 on success, -1 otherwise.
*/
int
virNetDevBandwidthUnplug(const char *brname,
unsigned int id)
{
int ret = -1;
int cmd_ret = 0;
virCommandPtr cmd = NULL;
char *class_id = NULL;
char *qdisc_id = NULL;
if (id <= 2) {
virReportError(VIR_ERR_INTERNAL_ERROR, _("Invalid class ID %d"), id);
return -1;
}
if (virAsprintf(&class_id, "1:%x", id) < 0 ||
virAsprintf(&qdisc_id, "%x:", id) < 0)
goto cleanup;
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "qdisc", "del", "dev", brname,
"handle", qdisc_id, NULL);
/* Don't threat tc errors as fatal, but
* try to remove as much as possible */
if (virCommandRun(cmd, &cmd_ret) < 0)
goto cleanup;
if (virNetDevBandwidthManipulateFilter(brname, NULL, id,
NULL, true, false) < 0)
goto cleanup;
virCommandFree(cmd);
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "class", "del", "dev", brname,
"classid", class_id, NULL);
if (virCommandRun(cmd, &cmd_ret) < 0)
goto cleanup;
ret = 0;
cleanup:
VIR_FREE(qdisc_id);
VIR_FREE(class_id);
virCommandFree(cmd);
return ret;
}
/**
* virNetDevBandwidthUpdateRate:
* @ifname: interface name
* @id: unique identifier
* @bandwidth: used to derive 'ceil' of class with @id
* @new_rate: new rate
*
* This function updates the 'rate' attribute of HTB class.
* It can be used whenever a new interface is plugged to a
* bridge to adjust average throughput of non guaranteed
* NICs.
*
* Returns 0 on success, -1 otherwise.
*/
int
virNetDevBandwidthUpdateRate(const char *ifname,
unsigned int id,
virNetDevBandwidthPtr bandwidth,
unsigned long long new_rate)
{
int ret = -1;
virCommandPtr cmd = NULL;
char *class_id = NULL;
char *rate = NULL;
char *ceil = NULL;
if (virAsprintf(&class_id, "1:%x", id) < 0 ||
virAsprintf(&rate, "%llukbps", new_rate) < 0 ||
virAsprintf(&ceil, "%llukbps", bandwidth->in->peak ?
bandwidth->in->peak :
bandwidth->in->average) < 0)
goto cleanup;
cmd = virCommandNew(TC);
virCommandAddArgList(cmd, "class", "change", "dev", ifname,
"classid", class_id, "htb", "rate", rate,
"ceil", ceil, NULL);
virNetDevBandwidthCmdAddOptimalQuantum(cmd, bandwidth->in);
if (virCommandRun(cmd, NULL) < 0)
goto cleanup;
ret = 0;
cleanup:
virCommandFree(cmd);
VIR_FREE(class_id);
VIR_FREE(rate);
VIR_FREE(ceil);
return ret;
}
/**
* virNetDevBandwidthUpdateFilter:
* @ifname: interface to operate on
* @ifmac_ptr: new MAC to update the filter with
* @id: filter ID
*
* Sometimes the host environment is so dynamic, that even a
* guest's MAC addresses change on the fly. When that happens we
* must update our QoS hierarchy so that the guest's traffic is
* placed into the correct QDiscs. This function updates the
* filter for the interface @ifname with the unique identifier
* @id so that it uses the new MAC address of the guest interface
* @ifmac_ptr.
*
* Returns: 0 on success,
* -1 on failure (with error reported).
*/
int
virNetDevBandwidthUpdateFilter(const char *ifname,
const virMacAddr *ifmac_ptr,
unsigned int id)
{
int ret = -1;
char *class_id = NULL;
if (virAsprintf(&class_id, "1:%x", id) < 0)
goto cleanup;
if (virNetDevBandwidthManipulateFilter(ifname, ifmac_ptr, id,
class_id, true, true) < 0)
goto cleanup;
ret = 0;
cleanup:
VIR_FREE(class_id);
return ret;
}
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