libvirt/src/util/virnetdevbandwidth.h
Michal Privoznik f3b422d9cc docs: Clarify 'burst' units for QoS
The burst attribute for bandwidth specifies how much bytes can be
transmitted in a single burst. Therefore, the unit is in
multiples of 1024 (thus kibibytes) not SI-like 1000. It has
always been like that.

The 'tc' output is still confusing though, for instance:

  # tc class add dev $DEV parent 1: classid 1:1 htb rate 1000kbps burst 2097152
  # tc class show dev vnet2
  class htb 1:1 root rate 8Mbit ceil 8Mbit burst 2Mb cburst 1600b

Please note that 2097152 = 2*1024*1024. Even the man page is
confusing. From tc(8):

  kb or k        Kilobytes
  mb or m        Megabytes

But I guess this is because 'tc' predates IEC standardisation of
binary multiples and thus can't change without breaking scripts
parsing its output.

And while at it, adjust _virNetDevBandwidthRate struct member
description, to make it obvious which members use SI/IEC units.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2022-01-04 16:40:10 +01:00

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C

/*
* 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/>.
*/
#pragma once
#include "internal.h"
#include "virmacaddr.h"
typedef struct _virNetDevBandwidthRate virNetDevBandwidthRate;
struct _virNetDevBandwidthRate {
unsigned long long average; /* kilobytes/s */
unsigned long long peak; /* kilobytes/s */
unsigned long long floor; /* kilobytes/s */
unsigned long long burst; /* kibibytes */
};
typedef struct _virNetDevBandwidth virNetDevBandwidth;
struct _virNetDevBandwidth {
virNetDevBandwidthRate *in;
virNetDevBandwidthRate *out;
};
void virNetDevBandwidthFree(virNetDevBandwidth *def);
G_DEFINE_AUTOPTR_CLEANUP_FUNC(virNetDevBandwidth, virNetDevBandwidthFree);
int virNetDevBandwidthSet(const char *ifname,
const virNetDevBandwidth *bandwidth,
bool hierarchical_class,
bool swapped)
G_GNUC_WARN_UNUSED_RESULT;
int virNetDevBandwidthClear(const char *ifname);
int virNetDevBandwidthCopy(virNetDevBandwidth **dest,
const virNetDevBandwidth *src)
ATTRIBUTE_NONNULL(1) G_GNUC_WARN_UNUSED_RESULT;
bool virNetDevBandwidthEqual(const virNetDevBandwidth *a, const virNetDevBandwidth *b);
int virNetDevBandwidthPlug(const char *brname,
virNetDevBandwidth *net_bandwidth,
const virMacAddr *ifmac_ptr,
virNetDevBandwidth *bandwidth,
unsigned int id)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4)
G_GNUC_WARN_UNUSED_RESULT;
int virNetDevBandwidthUnplug(const char *brname,
unsigned int id)
ATTRIBUTE_NONNULL(1) G_GNUC_WARN_UNUSED_RESULT;
int virNetDevBandwidthUpdateRate(const char *ifname,
unsigned int id,
virNetDevBandwidth *bandwidth,
unsigned long long new_rate)
ATTRIBUTE_NONNULL(1) G_GNUC_WARN_UNUSED_RESULT;
int virNetDevBandwidthUpdateFilter(const char *ifname,
const virMacAddr *ifmac_ptr,
unsigned int id)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
G_GNUC_WARN_UNUSED_RESULT;
int virNetDevBandwidthSetRootQDisc(const char *ifname,
const char *qdisc)
G_GNUC_NO_INLINE;