7:09 p.m.
Happy Holidays! :-)
This small series adds support for specifying vif outgoing rate limits
in Xen. The first patch adds support for converting rate limits between
xl/xm config and domXML, along with introducing a test for the conversion
logic. The second patch adds outgoing rate limiting to the libxl driver.
Jim Fehlig (2):
xenconfig: support parsing and formatting vif bandwidth
libxl: support vif outgoing bandwidth QoS
src/libxl/libxl_conf.c | 39 ++++++++++++++++++
src/xenconfig/xen_common.c | 77 ++++++++++++++++++++++++++++++++++++
tests/xlconfigdata/test-vif-rate.cfg | 26 ++++++++++++
tests/xlconfigdata/test-vif-rate.xml | 57 ++++++++++++++++++++++++++
tests/xlconfigtest.c | 1 +
5 files changed, 200 insertions(+)
create mode 100644 tests/xlconfigdata/test-vif-rate.cfg
create mode 100644 tests/xlconfigdata/test-vif-rate.xml
--
2.1.4
7:09 p.m.
New subject: [libvirt] [PATCH 1/2] xenconfig: support parsing and formatting vif bandwidth
Both xm and xl config have long supported specifying vif rate
limiting, e.g.
vif = [ 'mac=00:16:3E:74:3d:76,bridge=br0,rate=10MB/s' ]
Add support for mapping rate to and from <bandwidth> in the xenconfig
parser and formatter. rate is mapped to the required 'average' attribute
of the <outbound> element, e.g.
<interface type='bridge'>
...
<bandwidth>
<outbound average='10240'/>
</bandwidth>
</interface>
Also add a unit test to check the conversion logic.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
---
I used a bit of code from libxlu_vif.c to implement xenParseVifRate()
instead of using the libxlutil lib directly, since in theory rate limiting
applies to the old xen driver (no libxl) as well.
src/xenconfig/xen_common.c | 77 ++++++++++++++++++++++++++++++++++++
tests/xlconfigdata/test-vif-rate.cfg | 26 ++++++++++++
tests/xlconfigdata/test-vif-rate.xml | 57 ++++++++++++++++++++++++++
tests/xlconfigtest.c | 1 +
4 files changed, 161 insertions(+)
diff --git a/src/xenconfig/xen_common.c b/src/xenconfig/xen_common.c
index 54f5791..b9f0344 100644
--- a/src/xenconfig/xen_common.c
+++ b/src/xenconfig/xen_common.c
@@ -28,6 +28,8 @@
#include <config.h>
+#include <regex.h>
+
#include "internal.h"
#include "virerror.h"
#include "virconf.h"
@@ -803,6 +805,46 @@ xenParseCharDev(virConfPtr conf, virDomainDefPtr def)
}
+static const char *vif_bytes_per_sec_re = "^[0-9]+[GMK]?[Bb]/s$";
+
+static int
+xenParseVifRate(char *rate, unsigned long long *kbytes_per_sec)
+{
+ regex_t rec;
+ char *suffix;
+ unsigned long long tmp;
+ int ret = -1;
+
+ regcomp(&rec, vif_bytes_per_sec_re, REG_EXTENDED|REG_NOSUB);
+ if (regexec(&rec, rate, 0, NULL, 0)) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Invalid rate '%s' specified"), rate);
+ goto cleanup;
+ }
+
+ if (virStrToLong_ull(rate, &suffix, 10, &tmp)) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Failed to parse rate '%s'"), rate);
+ goto cleanup;
+ }
+
+ if (*suffix == 'G')
+ tmp *= 1024 * 1024;
+ else if (*suffix == 'M')
+ tmp *= 1024;
+
+ if (*suffix == 'b' || *(suffix + 1) == 'b')
+ tmp /= 8;
+
+ *kbytes_per_sec = tmp;
+ ret = 0;
+
+ cleanup:
+ regfree(&rec);
+ return ret;
+}
+
+
static int
xenParseVif(virConfPtr conf, virDomainDefPtr def)
{
@@ -819,6 +861,7 @@ xenParseVif(virConfPtr conf, virDomainDefPtr def)
char mac[18];
char bridge[50];
char vifname[50];
+ char rate[50];
char *key;
bridge[0] = '\0';
@@ -827,6 +870,7 @@ xenParseVif(virConfPtr conf, virDomainDefPtr def)
model[0] = '\0';
type[0] = '\0';
vifname[0] = '\0';
+ rate[0] = '\0';
if ((list->type != VIR_CONF_STRING) || (list->str == NULL))
goto skipnic;
@@ -892,6 +936,13 @@ xenParseVif(virConfPtr conf, virDomainDefPtr def)
_("IP %s too big for destination"),
data);
goto skipnic;
}
+ } else if (STRPREFIX(key, "rate=")) {
+ int len = nextkey ? (nextkey - data) : sizeof(rate) - 1;
+ if (virStrncpy(rate, data, len, sizeof(rate)) == NULL) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("rate %s too big for destination"),
data);
+ goto skipnic;
+ }
}
while (nextkey && (nextkey[0] == ',' ||
@@ -942,6 +993,29 @@ xenParseVif(virConfPtr conf, virDomainDefPtr def)
VIR_STRDUP(net->ifname, vifname) < 0)
goto cleanup;
+ if (rate[0]) {
+ char *p;
+ virNetDevBandwidthPtr bandwidth;
+ unsigned long long kbytes_per_sec;
+
+ p = strchr(rate, '@');
+ if (p != NULL)
+ *p = 0;
+
+ if (xenParseVifRate(rate, &kbytes_per_sec) < 0)
+ goto cleanup;
+
+ if (VIR_ALLOC(bandwidth) < 0)
+ goto cleanup;
+ if (VIR_ALLOC(bandwidth->out) < 0) {
+ VIR_FREE(bandwidth);
+ goto cleanup;
+ }
+
+ bandwidth->out->average = kbytes_per_sec;
+ net->bandwidth = bandwidth;
+ }
+
if (VIR_APPEND_ELEMENT(def->nets, def->nnets, net) < 0)
goto cleanup;
@@ -1184,6 +1258,9 @@ xenFormatNet(virConnectPtr conn,
virBufferAsprintf(&buf, ",vifname=%s",
net->ifname);
+ if (net->bandwidth && net->bandwidth->out &&
net->bandwidth->out->average)
+ virBufferAsprintf(&buf, ",rate=%lluKB/s",
net->bandwidth->out->average);
+
if (virBufferCheckError(&buf) < 0)
goto cleanup;
diff --git a/tests/xlconfigdata/test-vif-rate.cfg b/tests/xlconfigdata/test-vif-rate.cfg
new file mode 100644
index 0000000..c5484dc
--- /dev/null
+++ b/tests/xlconfigdata/test-vif-rate.cfg
@@ -0,0 +1,26 @@
+name = "XenGuest2"
+uuid = "c7a5fdb2-cdaf-9455-926a-d65c16db1809"
+maxmem = 579
+memory = 394
+vcpus = 1
+pae = 1
+acpi = 1
+apic = 1
+hap = 0
+viridian = 0
+rtc_timeoffset = 0
+localtime = 0
+on_poweroff = "destroy"
+on_reboot = "restart"
+on_crash = "restart"
+device_model = "/usr/lib/xen/bin/qemu-dm"
+sdl = 0
+vnc = 1
+vncunused = 1
+vnclisten = "127.0.0.1"
+vif = [
"mac=00:16:3e:66:92:9c,bridge=xenbr1,script=vif-bridge,model=e1000,rate=10240KB/s"
]
+parallel = "none"
+serial = "none"
+builder = "hvm"
+boot = "d"
+disk = [ "/dev/HostVG/XenGuest2,raw,hda,w,backendtype=phy",
"/var/lib/libvirt/images/XenGuest2-home,qcow2,hdb,w,backendtype=qdisk",
"/root/boot.iso,raw,hdc,r,backendtype=qdisk,devtype=cdrom" ]
diff --git a/tests/xlconfigdata/test-vif-rate.xml b/tests/xlconfigdata/test-vif-rate.xml
new file mode 100644
index 0000000..29f0f79
--- /dev/null
+++ b/tests/xlconfigdata/test-vif-rate.xml
@@ -0,0 +1,57 @@
+<domain type='xen'>
+ <name>XenGuest2</name>
+ <uuid>c7a5fdb2-cdaf-9455-926a-d65c16db1809</uuid>
+ <memory unit='KiB'>592896</memory>
+ <currentMemory unit='KiB'>403456</currentMemory>
+ <vcpu placement='static'>1</vcpu>
+ <os>
+ <type arch='x86_64' machine='xenfv'>hvm</type>
+ <loader type='rom'>/usr/lib/xen/boot/hvmloader</loader>
+ <boot dev='cdrom'/>
+ </os>
+ <features>
+ <acpi/>
+ <apic/>
+ <pae/>
+ </features>
+ <clock offset='variable' adjustment='0' basis='utc'/>
+ <on_poweroff>destroy</on_poweroff>
+ <on_reboot>restart</on_reboot>
+ <on_crash>restart</on_crash>
+ <devices>
+ <emulator>/usr/lib/xen/bin/qemu-dm</emulator>
+ <disk type='block' device='disk'>
+ <driver name='phy' type='raw'/>
+ <source dev='/dev/HostVG/XenGuest2'/>
+ <target dev='hda' bus='ide'/>
+ <address type='drive' controller='0' bus='0'
target='0' unit='0'/>
+ </disk>
+ <disk type='file' device='disk'>
+ <driver name='qemu' type='qcow2'/>
+ <source file='/var/lib/libvirt/images/XenGuest2-home'/>
+ <target dev='hdb' bus='ide'/>
+ <address type='drive' controller='0' bus='0'
target='0' unit='1'/>
+ </disk>
+ <disk type='file' device='cdrom'>
+ <driver name='qemu' type='raw'/>
+ <source file='/root/boot.iso'/>
+ <target dev='hdc' bus='ide'/>
+ <readonly/>
+ <address type='drive' controller='0' bus='1'
target='0' unit='0'/>
+ </disk>
+ <interface type='bridge'>
+ <mac address='00:16:3e:66:92:9c'/>
+ <source bridge='xenbr1'/>
+ <bandwidth>
+ <outbound average='10240'/>
+ </bandwidth>
+ <script path='vif-bridge'/>
+ <model type='e1000'/>
+ </interface>
+ <input type='mouse' bus='ps2'/>
+ <input type='keyboard' bus='ps2'/>
+ <graphics type='vnc' port='-1' autoport='yes'
listen='127.0.0.1'>
+ <listen type='address' address='127.0.0.1'/>
+ </graphics>
+ </devices>
+</domain>
diff --git a/tests/xlconfigtest.c b/tests/xlconfigtest.c
index 1db11e7..e997009 100644
--- a/tests/xlconfigtest.c
+++ b/tests/xlconfigtest.c
@@ -196,6 +196,7 @@ mymain(void)
DO_TEST("new-disk");
DO_TEST("spice");
DO_TEST("spice-features");
+ DO_TEST("vif-rate");
#ifdef LIBXL_HAVE_BUILDINFO_USBDEVICE_LIST
DO_TEST("fullvirt-multiusb");
--
2.1.4
8:48 a.m.
New subject: [libvirt] [PATCH 1/2] xenconfig: support parsing and formatting vif bandwidth
On 29.12.2015 02:09, Jim Fehlig wrote:
Both xm and xl config have long supported specifying vif rate
limiting, e.g.
vif = [ 'mac=00:16:3E:74:3d:76,bridge=br0,rate=10MB/s' ]
Add support for mapping rate to and from <bandwidth> in the xenconfig
parser and formatter. rate is mapped to the required 'average' attribute
of the <outbound> element, e.g.
<interface type='bridge'>
...
<bandwidth>
<outbound average='10240'/>
</bandwidth>
</interface>
Also add a unit test to check the conversion logic.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
---
I used a bit of code from libxlu_vif.c to implement xenParseVifRate()
instead of using the libxlutil lib directly, since in theory rate limiting
applies to the old xen driver (no libxl) as well.
src/xenconfig/xen_common.c | 77 ++++++++++++++++++++++++++++++++++++
tests/xlconfigdata/test-vif-rate.cfg | 26 ++++++++++++
tests/xlconfigdata/test-vif-rate.xml | 57 ++++++++++++++++++++++++++
tests/xlconfigtest.c | 1 +
4 files changed, 161 insertions(+)
ACK
Michal
11:21 p.m.
New subject: [libvirt] [PATCH 1/2] xenconfig: support parsing and formatting vif bandwidth
On 01/07/2016 07:48 AM, Michal Privoznik wrote:
On 29.12.2015 02:09, Jim Fehlig wrote:
> Both xm and xl config have long supported specifying vif rate
> limiting, e.g.
>
> vif = [ 'mac=00:16:3E:74:3d:76,bridge=br0,rate=10MB/s' ]
>
> Add support for mapping rate to and from <bandwidth> in the xenconfig
> parser and formatter. rate is mapped to the required 'average' attribute
> of the <outbound> element, e.g.
>
> <interface type='bridge'>
> ...
> <bandwidth>
> <outbound average='10240'/>
> </bandwidth>
> </interface>
>
> Also add a unit test to check the conversion logic.
>
> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
> ---
>
> I used a bit of code from libxlu_vif.c to implement xenParseVifRate()
> instead of using the libxlutil lib directly, since in theory rate limiting
> applies to the old xen driver (no libxl) as well.
>
> src/xenconfig/xen_common.c | 77 ++++++++++++++++++++++++++++++++++++
> tests/xlconfigdata/test-vif-rate.cfg | 26 ++++++++++++
> tests/xlconfigdata/test-vif-rate.xml | 57 ++++++++++++++++++++++++++
> tests/xlconfigtest.c | 1 +
> 4 files changed, 161 insertions(+)
ACK
Hi Michal,
Thanks a lot for taking a look at this series! Note that I posted a V2 earlier
this week which includes support for parsing/formatting vif bandwidth in sexpr
config too
https://www.redhat.com/archives/libvir-list/2016-January/msg00045.html
Unfortunately it results in some changes to this patch, so I think it would be
best to peek at the V2 series before pushing it.
Regards,
Jim
7:09 p.m.
New subject: [libvirt] [PATCH 2/2] libxl: support vif outgoing bandwidth QoS
The libxl_device_nic structure supports specifying an outgoing rate
limit based on a time interval and bytes allowed per interval. In xl
config a rate limit is specified as "<RATE>/s@<INTERVAL>". INTERVAL
is optional and defaults to 50ms.
libvirt expresses outgoing limits by average (required), peak, burst,
and floor attributes in units of KB/s. This patch supports the outgoing
bandwidth limit by converting the average KB/s to bytes per interval
based on the same default interval (50ms) used by xl.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
---
src/libxl/libxl_conf.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index 23c74e7..6320421 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -1093,6 +1093,7 @@ libxlMakeNic(virDomainDefPtr def,
{
bool ioemu_nic = def->os.type == VIR_DOMAIN_OSTYPE_HVM;
virDomainNetType actual_type = virDomainNetGetActualType(l_nic);
+ virNetDevBandwidthPtr actual_bw;
/* TODO: Where is mtu stored?
*
@@ -1206,6 +1207,44 @@ libxlMakeNic(virDomainDefPtr def,
#endif
}
+ /*
+ * Set bandwidth.
+ * From $xen-sources/docs/misc/xl-network-configuration.markdown:
+ *
+ *
+ * Specifies the rate at which the outgoing traffic will be limited to.
+ * The default if this keyword is not specified is unlimited.
+ *
+ * The rate may be specified as "<RATE>/s" or optionally
"<RATE>/s@<INTERVAL>".
+ *
+ * `RATE` is in bytes and can accept suffixes:
+ * GB, MB, KB, B for bytes.
+ * Gb, Mb, Kb, b for bits.
+ * `INTERVAL` is in microseconds and can accept suffixes: ms, us, s.
+ * It determines the frequency at which the vif transmission credit
+ * is replenished. The default is 50ms.
+
+ * Vif rate limiting is credit-based. It means that for "1MB/s@20ms",
+ * the available credit will be equivalent of the traffic you would have
+ * done at "1MB/s" during 20ms. This will results in a credit of 20,000
+ * bytes replenished every 20,000 us.
+ *
+ *
+ * libvirt doesn't support the notion of rate limiting over an interval.
+ * Similar to xl's behavior when interval is not specified, set a default
+ * interval of 50ms and calculate the number of bytes per interval based
+ * on the specified average bandwidth.
+ */
+ actual_bw = virDomainNetGetActualBandwidth(l_nic);
+ if (actual_bw && actual_bw->out && actual_bw->out->average)
{
+ uint64_t bytes_per_sec = actual_bw->out->average * 1024;
+ uint64_t bytes_per_interval =
+ (((uint64_t) bytes_per_sec * 50000UL) / 1000000UL);
+
+ x_nic->rate_bytes_per_interval = bytes_per_interval;
+ x_nic->rate_interval_usecs = 50000UL;
+ }
+
return 0;
}
--
2.1.4
8:48 a.m.
New subject: [libvirt] [PATCH 2/2] libxl: support vif outgoing bandwidth QoS
On 29.12.2015 02:09, Jim Fehlig wrote:
The libxl_device_nic structure supports specifying an outgoing rate
limit based on a time interval and bytes allowed per interval. In xl
config a rate limit is specified as "<RATE>/s@<INTERVAL>".
INTERVAL
is optional and defaults to 50ms.
libvirt expresses outgoing limits by average (required), peak, burst,
and floor attributes in units of KB/s. This patch supports the outgoing
bandwidth limit by converting the average KB/s to bytes per interval
based on the same default interval (50ms) used by xl.
Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
---
src/libxl/libxl_conf.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
index 23c74e7..6320421 100644
--- a/src/libxl/libxl_conf.c
+++ b/src/libxl/libxl_conf.c
@@ -1093,6 +1093,7 @@ libxlMakeNic(virDomainDefPtr def,
{
bool ioemu_nic = def->os.type == VIR_DOMAIN_OSTYPE_HVM;
virDomainNetType actual_type = virDomainNetGetActualType(l_nic);
+ virNetDevBandwidthPtr actual_bw;
/* TODO: Where is mtu stored?
*
@@ -1206,6 +1207,44 @@ libxlMakeNic(virDomainDefPtr def,
#endif
}
+ /*
+ * Set bandwidth.
+ * From $xen-sources/docs/misc/xl-network-configuration.markdown:
+ *
+ *
+ * Specifies the rate at which the outgoing traffic will be limited to.
+ * The default if this keyword is not specified is unlimited.
+ *
+ * The rate may be specified as "<RATE>/s" or optionally
"<RATE>/s@<INTERVAL>".
+ *
+ * `RATE` is in bytes and can accept suffixes:
+ * GB, MB, KB, B for bytes.
+ * Gb, Mb, Kb, b for bits.
+ * `INTERVAL` is in microseconds and can accept suffixes: ms, us, s.
+ * It determines the frequency at which the vif transmission credit
+ * is replenished. The default is 50ms.
+
+ * Vif rate limiting is credit-based. It means that for "1MB/s@20ms",
+ * the available credit will be equivalent of the traffic you would have
+ * done at "1MB/s" during 20ms. This will results in a credit of 20,000
+ * bytes replenished every 20,000 us.
+ *
+ *
+ * libvirt doesn't support the notion of rate limiting over an interval.
+ * Similar to xl's behavior when interval is not specified, set a default
+ * interval of 50ms and calculate the number of bytes per interval based
+ * on the specified average bandwidth.
+ */
+ actual_bw = virDomainNetGetActualBandwidth(l_nic);
+ if (actual_bw && actual_bw->out && actual_bw->out->average)
{
+ uint64_t bytes_per_sec = actual_bw->out->average * 1024;
+ uint64_t bytes_per_interval =
+ (((uint64_t) bytes_per_sec * 50000UL) / 1000000UL);
+
+ x_nic->rate_bytes_per_interval = bytes_per_interval;
+ x_nic->rate_interval_usecs = 50000UL;
+ }
+
Interesting. I'd expect:
x_nic->rate_bytes_per_interval = bytes_per_sec;
x_nic->rate_interval_usecs = 1000*1000;
I mean, if I understood the xl way of rate limiting correctly, one says
how much bytes can be sent for how long. so for 1MB/s I'd expect to send
1024*1024 bytes each second.
Or am I missing something?
Michal
11:11 p.m.
New subject: [libvirt] [PATCH 2/2] libxl: support vif outgoing bandwidth QoS
On 01/07/2016 07:48 AM, Michal Privoznik wrote:
On 29.12.2015 02:09, Jim Fehlig wrote:
> The libxl_device_nic structure supports specifying an outgoing rate
> limit based on a time interval and bytes allowed per interval. In xl
> config a rate limit is specified as "<RATE>/s@<INTERVAL>".
INTERVAL
> is optional and defaults to 50ms.
>
> libvirt expresses outgoing limits by average (required), peak, burst,
> and floor attributes in units of KB/s. This patch supports the outgoing
> bandwidth limit by converting the average KB/s to bytes per interval
> based on the same default interval (50ms) used by xl.
>
> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
> ---
> src/libxl/libxl_conf.c | 39 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 39 insertions(+)
>
> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
> index 23c74e7..6320421 100644
> --- a/src/libxl/libxl_conf.c
> +++ b/src/libxl/libxl_conf.c
> @@ -1093,6 +1093,7 @@ libxlMakeNic(virDomainDefPtr def,
> {
> bool ioemu_nic = def->os.type == VIR_DOMAIN_OSTYPE_HVM;
> virDomainNetType actual_type = virDomainNetGetActualType(l_nic);
> + virNetDevBandwidthPtr actual_bw;
>
> /* TODO: Where is mtu stored?
> *
> @@ -1206,6 +1207,44 @@ libxlMakeNic(virDomainDefPtr def,
> #endif
> }
>
> + /*
> + * Set bandwidth.
> + * From $xen-sources/docs/misc/xl-network-configuration.markdown:
> + *
> + *
> + * Specifies the rate at which the outgoing traffic will be limited to.
> + * The default if this keyword is not specified is unlimited.
> + *
> + * The rate may be specified as "<RATE>/s" or optionally
"<RATE>/s@<INTERVAL>".
> + *
> + * `RATE` is in bytes and can accept suffixes:
> + * GB, MB, KB, B for bytes.
> + * Gb, Mb, Kb, b for bits.
> + * `INTERVAL` is in microseconds and can accept suffixes: ms, us, s.
> + * It determines the frequency at which the vif transmission credit
> + * is replenished. The default is 50ms.
> +
> + * Vif rate limiting is credit-based. It means that for "1MB/s@20ms",
> + * the available credit will be equivalent of the traffic you would have
> + * done at "1MB/s" during 20ms. This will results in a credit of
20,000
> + * bytes replenished every 20,000 us.
> + *
> + *
> + * libvirt doesn't support the notion of rate limiting over an interval.
> + * Similar to xl's behavior when interval is not specified, set a default
> + * interval of 50ms and calculate the number of bytes per interval based
> + * on the specified average bandwidth.
> + */
> + actual_bw = virDomainNetGetActualBandwidth(l_nic);
> + if (actual_bw && actual_bw->out &&
actual_bw->out->average) {
> + uint64_t bytes_per_sec = actual_bw->out->average * 1024;
> + uint64_t bytes_per_interval =
> + (((uint64_t) bytes_per_sec * 50000UL) / 1000000UL);
> +
> + x_nic->rate_bytes_per_interval = bytes_per_interval;
> + x_nic->rate_interval_usecs = 50000UL;
> + }
> +
Interesting. I'd expect:
x_nic->rate_bytes_per_interval = bytes_per_sec;
x_nic->rate_interval_usecs = 1000*1000;
For the most part I mimicked the Xen code and wanted to stick with the default
interval of 50ms, which has been the default for a long time. It is even
mentioned in some old RHEL5 docs
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/5/...
BTW, here is the Xen code that inspired this logic
http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=tools/libxl/libxlu_vif....
rate_bytes_per_interval is set to (bytes/s * interval us)/1000000us
I guess we are saying the same thing, you're just setting interval to 1s (thus
rate_bytes_per_interval == bytes_per_sec) instead of the historical 50ms :-).
I mean, if I understood the xl way of rate limiting correctly, one says
how much bytes can be sent for how long. so for 1MB/s I'd expect to send
1024*1024 bytes each second.
Or am I missing something?
Does the above explanation make sense? I might be missing something :-). CC'd a
few Xen tools maintainer just in case.
Regards,
Jim
9:32 a.m.
New subject: [libvirt] [PATCH 2/2] libxl: support vif outgoing bandwidth QoS
On 08.01.2016 06:11, Jim Fehlig wrote:
On 01/07/2016 07:48 AM, Michal Privoznik wrote:
> On 29.12.2015 02:09, Jim Fehlig wrote:
>> The libxl_device_nic structure supports specifying an outgoing rate
>> limit based on a time interval and bytes allowed per interval. In xl
>> config a rate limit is specified as "<RATE>/s@<INTERVAL>".
INTERVAL
>> is optional and defaults to 50ms.
>>
>> libvirt expresses outgoing limits by average (required), peak, burst,
>> and floor attributes in units of KB/s. This patch supports the outgoing
>> bandwidth limit by converting the average KB/s to bytes per interval
>> based on the same default interval (50ms) used by xl.
>>
>> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com>
>> ---
>> src/libxl/libxl_conf.c | 39 +++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 39 insertions(+)
>>
>> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
>> index 23c74e7..6320421 100644
>> --- a/src/libxl/libxl_conf.c
>> +++ b/src/libxl/libxl_conf.c
>> @@ -1093,6 +1093,7 @@ libxlMakeNic(virDomainDefPtr def,
>> {
>> bool ioemu_nic = def->os.type == VIR_DOMAIN_OSTYPE_HVM;
>> virDomainNetType actual_type = virDomainNetGetActualType(l_nic);
>> + virNetDevBandwidthPtr actual_bw;
>>
>> /* TODO: Where is mtu stored?
>> *
>> @@ -1206,6 +1207,44 @@ libxlMakeNic(virDomainDefPtr def,
>> #endif
>> }
>>
>> + /*
>> + * Set bandwidth.
>> + * From $xen-sources/docs/misc/xl-network-configuration.markdown:
>> + *
>> + *
>> + * Specifies the rate at which the outgoing traffic will be limited to.
>> + * The default if this keyword is not specified is unlimited.
>> + *
>> + * The rate may be specified as "<RATE>/s" or optionally
"<RATE>/s@<INTERVAL>".
>> + *
>> + * `RATE` is in bytes and can accept suffixes:
>> + * GB, MB, KB, B for bytes.
>> + * Gb, Mb, Kb, b for bits.
>> + * `INTERVAL` is in microseconds and can accept suffixes: ms, us, s.
>> + * It determines the frequency at which the vif transmission credit
>> + * is replenished. The default is 50ms.
>> +
>> + * Vif rate limiting is credit-based. It means that for
"1MB/s@20ms",
>> + * the available credit will be equivalent of the traffic you would have
>> + * done at "1MB/s" during 20ms. This will results in a credit of
20,000
>> + * bytes replenished every 20,000 us.
>> + *
>> + *
>> + * libvirt doesn't support the notion of rate limiting over an
interval.
>> + * Similar to xl's behavior when interval is not specified, set a
default
>> + * interval of 50ms and calculate the number of bytes per interval based
>> + * on the specified average bandwidth.
>> + */
>> + actual_bw = virDomainNetGetActualBandwidth(l_nic);
>> + if (actual_bw && actual_bw->out &&
actual_bw->out->average) {
>> + uint64_t bytes_per_sec = actual_bw->out->average * 1024;
>> + uint64_t bytes_per_interval =
>> + (((uint64_t) bytes_per_sec * 50000UL) / 1000000UL);
>> +
>> + x_nic->rate_bytes_per_interval = bytes_per_interval;
>> + x_nic->rate_interval_usecs = 50000UL;
>> + }
>> +
> Interesting. I'd expect:
>
> x_nic->rate_bytes_per_interval = bytes_per_sec;
> x_nic->rate_interval_usecs = 1000*1000;
For the most part I mimicked the Xen code and wanted to stick with the default
interval of 50ms, which has been the default for a long time. It is even
mentioned in some old RHEL5 docs
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/5/...
BTW, here is the Xen code that inspired this logic
http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=tools/libxl/libxlu_vif....
rate_bytes_per_interval is set to (bytes/s * interval us)/1000000us
I guess we are saying the same thing, you're just setting interval to 1s (thus
rate_bytes_per_interval == bytes_per_sec) instead of the historical 50ms :-).
>
> I mean, if I understood the xl way of rate limiting correctly, one says
> how much bytes can be sent for how long. so for 1MB/s I'd expect to send
> 1024*1024 bytes each second.
>
> Or am I missing something?
Does the above explanation make sense? I might be missing something :-). CC'd a
few Xen tools maintainer just in case.
Yep, it makes sense now. So let me review v2.
Michal
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Jim Fehlig -
Michal Privoznik