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libxl: support vif outgoing bandwidth QoS

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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@suse.com>
This commit is contained in:
Jim Fehlig 2015-12-28 17:26:58 -07:00
parent ec63000a62
commit f988ecfb34
1 changed files with 39 additions and 0 deletions
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39
src/libxl/libxl_conf.c
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@ -1093,6 +1093,7 @@ libxlMakeNic(virDomainDefPtr def,
{ {
bool ioemu_nic = def->os.type == VIR_DOMAIN_OSTYPE_HVM; bool ioemu_nic = def->os.type == VIR_DOMAIN_OSTYPE_HVM;
virDomainNetType actual_type = virDomainNetGetActualType(l_nic); virDomainNetType actual_type = virDomainNetGetActualType(l_nic);
virNetDevBandwidthPtr actual_bw;
/* TODO: Where is mtu stored? /* TODO: Where is mtu stored?
* *
@ -1206,6 +1207,44 @@ libxlMakeNic(virDomainDefPtr def,
#endif #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; return 0;
} }