[libvirt] [PATCH 0/9] Yet another version of CAT stuff (no idea about the version number)
Eli
qiaoliyong at gmail.com
Thu Dec 14 11:46:27 UTC 2017
>>
>> @Eli: Can you help with the testing?
>>
It seems the interface is only implement the isolated case, I remember
that you have proposed that for some overlap case?
I have not see the whole patch set yet, but I have some quick testing on
you patch, will try to find more time to review patches (Currently I am
maintain another daemon software which is dedicated for RDT feature
called RMD)
Only the issue 1 is the true issue, for the others, I think they should
be discussed, or be treat as the 'known issue'.
My env:
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 56320K
NUMA node0 CPU(s): 0-21,44-65
NUMA node1 CPU(s): 22-43,66-87
virsh capabilities:
171 <cache>
172 <bank id='0' level='3' type='both' size='55' unit='MiB'
cpus='0-21,44-65'>
173 <control granularity='2816' unit='KiB' type='both'
maxAllocs='16'/>
174 </bank>
175 <bank id='1' level='3' type='both' size='55' unit='MiB'
cpus='22-43,66-87'>
176 <control granularity='2816' unit='KiB' type='both'
maxAllocs='16'/>
177 </bank>
178 </cache>
*Issue:
*1. Doesn't support asynchronous cache allocation. e.g, I need provide
all cache allocation require ways, but I am only care about the
allocation on one of the cache id, cause the VM won't be schedule to
another cache (socket).
So I got this error if I define the domain like this:
<vcpu placement='static'>6</vcpu>
<cputune>
<emulatorpin cpuset='0,37-38,44,81-82'/>
<cachetune vcpus='0-4'>
* <cache id='0' level='3' type='both' size='2816' unit='KiB'/>
^^^ not provide cache id='1'
* </cachetune>
root at s2600wt:~# virsh start kvm-cat
error: Failed to start domain kvm-cat
error: Cannot write into schemata file
'/sys/fs/resctrl/qemu-qemu-13-kvm-cat-0-4/schemata': Invalid argument
This behavior is not correct.
I expect the CBM will be look like:
root at s2600wt:/sys/fs/resctrl# cat qemu-qemu-14-kvm-cat-0-4/*
000000,00000000,00000000
L3:0=80;1=fffff *(no matter what it is, cause my VM won't be schedule on
it, ether I have deinfe the vcpu->cpu pining or, I assume that kernel
won't schedule it to cache 1)
*Or at least, restrict xml when I define this domain, tell me I need to
provide all cache ids (even if I have 4 cache but I only run my VM on
'cache 0')
*
*2. cache way fragment (no good answers)
I see that for now we allocate cache ways start from the low bits, newly
created VM will allocate cache from the next way, if some of the VM
(allocated ways in the middle, eg it's schemata is 00100) destroyed, and
that slot (1 cache way) may not fit others and it will be wasted, But,
how can we handle this, seems no good way, rearrangement? That will lead
cache missing in a time window I think.
3. The admin/user should manually operate the default resource group,
that's is to say, after resctrl is mounted, the admin/user should
manually change the schemata of default group. Will libvirt provide
interface/API to handle it?
4. Will provide some APIs like `FreeCacheWay` to end user to see how
many cache ways could be allocated on the host?
For other users/orchestrator (nova), they may need to know if a VM
can schedule on the host, but the cache ways is not liner, it may have
fragment.
5, What if other application want to have some shared cache ways with
some of the VM?
Libvirt for now try to read all of the resource group (instead of
maintain the consumed cache ways itself), so if another resource group
was created under /sys/fs/resctl, and the schemata of it is "FFFFF",
then libvirt will report not enough room for new VM. But the user
actually want to have another Appliation(e.g. ovs, dpdk pmds) share
cache ways with the VM created by libvirt.
**
I will try to more cases..
Thanks Eli.
>> Martin Kletzander (9):
>> Rename virResctrlInfo to virResctrlInfoPerCache
>> util: Add virResctrlInfo
>> conf: Use virResctrlInfo in capabilities
>> util: Remove now-unneeded resctrl functions
>> resctrl: Add functions to work with resctrl allocations
>> conf: Add support for cputune/cachetune
>> tests: Add virresctrltest
>> qemu: Add support for resctrl
>> docs: Add CAT (resctrl) support into news.xml
>>
>> docs/formatdomain.html.in <http://formatdomain.html.in>
>> | 54 +
>> docs/news.xml | 9 +
>> docs/schemas/domaincommon.rng | 32 +
>> po/POTFILES.in | 1 +
>> src/Makefile.am | 2 +-
>> src/conf/capabilities.c | 55 +-
>> src/conf/capabilities.h | 4 +-
>> src/conf/domain_conf.c | 251 ++++
>> src/conf/domain_conf.h | 13 +
>> src/libvirt_private.syms | 16 +-
>> src/qemu/qemu_process.c | 61 +-
>> src/util/virresctrl.c | 1380
>> ++++++++++++++++++--
>> src/util/virresctrl.h | 86 +-
>> src/util/virresctrlpriv.h | 27 +
>> tests/Makefile.am | 8 +-
>> tests/genericxml2xmlindata/cachetune-cdp.xml | 36 +
>> .../cachetune-colliding-allocs.xml | 30 +
>> .../cachetune-colliding-tunes.xml | 32 +
>> .../cachetune-colliding-types.xml | 30 +
>> tests/genericxml2xmlindata/cachetune-small.xml | 29 +
>> tests/genericxml2xmlindata/cachetune.xml | 33 +
>> tests/genericxml2xmltest.c | 10 +
>> tests/virresctrldata/resctrl-cdp.schemata | 2 +
>> .../virresctrldata/resctrl-skx-twocaches.schemata | 1 +
>> tests/virresctrldata/resctrl-skx.schemata | 1 +
>> tests/virresctrldata/resctrl.schemata | 1 +
>> tests/virresctrltest.c | 102 ++
>> 27 files changed, 2174 insertions(+), 132 deletions(-)
>> create mode 100644 src/util/virresctrlpriv.h
>> create mode 100644 tests/genericxml2xmlindata/cachetune-cdp.xml
>> create mode 100644
>> tests/genericxml2xmlindata/cachetune-colliding-allocs.xml
>> create mode 100644
>> tests/genericxml2xmlindata/cachetune-colliding-tunes.xml
>> create mode 100644
>> tests/genericxml2xmlindata/cachetune-colliding-types.xml
>> create mode 100644 tests/genericxml2xmlindata/cachetune-small.xml
>> create mode 100644 tests/genericxml2xmlindata/cachetune.xml
>> create mode 100644 tests/virresctrldata/resctrl-cdp.schemata
>> create mode 100644
>> tests/virresctrldata/resctrl-skx-twocaches.schemata
>> create mode 100644 tests/virresctrldata/resctrl-skx.schemata
>> create mode 100644 tests/virresctrldata/resctrl.schemata
>> create mode 100644 tests/virresctrltest.c
>>
>> --
>> 2.15.1
>>
>>
>
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