| Message ID | 20240715221245.12435-2-yichen.wang@bytedance.com |
|---|---|
| State | New |
| Headers | show |
| Series | Implement QATzip compression method | expand |
> -----Original Message----- > From: Yichen Wang <yichen.wang@bytedance.com> > Sent: Tuesday, July 16, 2024 6:13 AM > To: Peter Xu <peterx@redhat.com>; Fabiano Rosas <farosas@suse.de>; Paolo > Bonzini <pbonzini@redhat.com>; Daniel P. Berrangé <berrange@redhat.com>; > Eduardo Habkost <eduardo@habkost.net>; Marc-André Lureau > <marcandre.lureau@redhat.com>; Thomas Huth <thuth@redhat.com>; Philippe > Mathieu-Daudé <philmd@linaro.org>; Eric Blake <eblake@redhat.com>; Markus > Armbruster <armbru@redhat.com>; Laurent Vivier <lvivier@redhat.com>; qemu- > devel@nongnu.org > Cc: Hao Xiang <hao.xiang@linux.dev>; Liu, Yuan1 <yuan1.liu@intel.com>; > Zou, Nanhai <nanhai.zou@intel.com>; Ho-Ren (Jack) Chuang > <horenchuang@bytedance.com>; Wang, Yichen <yichen.wang@bytedance.com> > Subject: [PATCH v6 1/5] docs/migration: add qatzip compression feature > > From: Yuan Liu <yuan1.liu@intel.com> > > add Intel QATzip compression method introduction > > Signed-off-by: Yuan Liu <yuan1.liu@intel.com> > Reviewed-by: Nanhai Zou <nanhai.zou@intel.com> > Reviewed-by: Peter Xu <peterx@redhat.com> > Reviewed-by: Yichen Wang <yichen.wang@bytedance.com> > --- > docs/devel/migration/features.rst | 1 + > docs/devel/migration/qatzip-compression.rst | 251 ++++++++++++++++++++ > 2 files changed, 252 insertions(+) > create mode 100644 docs/devel/migration/qatzip-compression.rst > > diff --git a/docs/devel/migration/features.rst > b/docs/devel/migration/features.rst > index 58f8fd9e16..8f431d52f9 100644 > --- a/docs/devel/migration/features.rst > +++ b/docs/devel/migration/features.rst > @@ -14,3 +14,4 @@ Migration has plenty of features to support different > use cases. > CPR > qpl-compression > uadk-compression > + qatzip-compression > diff --git a/docs/devel/migration/qatzip-compression.rst > b/docs/devel/migration/qatzip-compression.rst > new file mode 100644 > index 0000000000..72fa3e2826 > --- /dev/null > +++ b/docs/devel/migration/qatzip-compression.rst > @@ -0,0 +1,251 @@ > +================== > +QATzip Compression > +================== > +In scenarios with limited network bandwidth, the ``QATzip`` solution can > help > +users save a lot of host CPU resources by accelerating compression and > +decompression through the Intel QuickAssist Technology(``QAT``) hardware. Hi Yichen Thanks for adding the part of Performance Testing with QATzip, I wonder if we can remove Performance Testing with QATzip part and directly add the following content. Here, we use a typical example of limited bandwidth to illustrate the advantages of QATzip. If the user is interested in qatzip, he still needs to verify the performance by himself. +The following test was conducted using 8 multifd channels and 10Gbps network +bandwidth. The results show that, compared to zstd, ``QATzip`` significantly +saves CPU resources on the sender and reduces migration time. Compared to the +uncompressed solution, ``QATzip`` greatly improves the dirty page processing +capability, indicated by the Pages per Second metric, and also reduces the +total migration time. + +:: + + VM Configuration: 16 vCPU and 64G memory + VM Workload: all vCPUs are idle and 54G memory is filled with Silesia data. + QAT Devices: 4 + |-----------|--------|---------|----------|----------|------|------| + |8 Channels |Total |down |throughput|pages per | send | recv | + | |time(ms)|time(ms) |(mbps) |second | cpu %| cpu% | + |-----------|--------|---------|----------|----------|------|------| + |qatzip | 16630| 28| 10467| 2940235| 160| 360| + |-----------|--------|---------|----------|----------|------|------| + |zstd | 20165| 24| 8579| 2391465| 810| 340| + |-----------|--------|---------|----------|----------|------|------| + |none | 46063| 40| 10848| 330240| 45| 85| + |-----------|--------|---------|----------|----------|------|------| > +``QATzip`` is a user space library which builds on top of the Intel > QuickAssist > +Technology user space library, to provide extended accelerated > compression and > +decompression services. > + > +For more ``QATzip`` introduction, please refer to `QATzip Introduction > +<https://github.com/intel/QATzip?tab=readme-ov-file#introductionl>`_ > + > +QATzip Compression Framework > +============================ > + > +:: > + > + +----------------+ > + | MultiFd Thread | > + +-------+--------+ > + | > + | compress/decompress > + +-------+--------+ > + | QATzip library | > + +-------+--------+ > + | > + +-------+--------+ > + | QAT library | > + +-------+--------+ > + | user space > + --------+--------------------- > + | kernel space > + +------+-------+ > + | QAT Driver | > + +------+-------+ > + | > + +------+-------+ > + | QAT Devices | > + +--------------+ > + > + > +QATzip Installation > +------------------- > + > +The ``QATzip`` installation package has been integrated into some Linux > +distributions and can be installed directly. For example, the Ubuntu > Server > +24.04 LTS system can be installed using below command > + > +.. code-block:: shell > + > + #apt search qatzip > + libqatzip-dev/noble 1.2.0-0ubuntu3 amd64 > + Intel QuickAssist user space library development files > + > + libqatzip3/noble 1.2.0-0ubuntu3 amd64 > + Intel QuickAssist user space library > + > + qatzip/noble,now 1.2.0-0ubuntu3 amd64 [installed] > + Compression user-space tool for Intel QuickAssist Technology > + > + #sudo apt install libqatzip-dev libqatzip3 qatzip > + > +If your system does not support the ``QATzip`` installation package, you > can > +use the source code to build and install, please refer to `QATzip source > code installation > +<https://github.com/intel/QATzip?tab=readme-ov-file#build-intel- > quickassist-technology-driver>`_ > + > +QAT Hardware Deployment > +----------------------- > + > +``QAT`` supports physical functions(PFs) and virtual functions(VFs) for > +deployment, and users can configure ``QAT`` resources for migration > according > +to actual needs. For more details about ``QAT`` deployment, please refer > to > +`Intel QuickAssist Technology Documentation > +<https://intel.github.io/quickassist/index.html>`_ > + > +For more ``QAT`` hardware introduction, please refer to `intel-quick- > assist-technology-overview > +<https://www.intel.com/content/www/us/en/architecture-and- > technology/intel-quick-assist-technology-overview.html>`_ > + > +How To Use QATzip Compression > +============================= > + > +1 - Install ``QATzip`` library > + > +2 - Build ``QEMU`` with ``--enable-qatzip`` parameter > + > + E.g. configure --target-list=x86_64-softmmu --enable-kvm ``--enable- > qatzip`` > + > +3 - Set ``migrate_set_parameter multifd-compression qatzip`` > + > +4 - Set ``migrate_set_parameter multifd-qatzip-level comp_level``, the > default > +comp_level value is 1, and it supports levels from 1 to 9 > + > + > +Performance Testing with QATzip > +=============================== > + > +Testing environment is being set as below: > + > +VM configuration:16 vCPU, 64G memory; > + > +VM Workload: all vCPUs are idle and 54G memory is filled with Silesia > data; > + > +QAT Devices: 4; > + > +Sender migration parameters: > + > +.. code-block:: shell > + > + migrate_set_capability multifd on > + migrate_set_parameter multifd-channels 2/4/8 > + migrate_set_parameter max-bandwidth 1G/10G > + migrate_set_parameter multifd-compression qatzip/zstd > + > +Receiver migration parameters: > + > +.. code-block:: shell > + > + migrate_set_capability multifd on > + migrate_set_parameter multifd-channels 2 > + migrate_set_parameter multifd-compression qatzip/zstd > + > +max-bandwidth: 1 GBps (Gbytes/sec) > + > +.. code-block:: text > + > + |-----------|--------|---------|----------|------|------| > + |2 Channels |Total |down |throughput| send | recv | > + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | > + |-----------|--------|---------|----------|------|------| > + |qatzip | 21607| 77| 8051| 88| 125| > + |-----------|--------|---------|----------|------|------| > + |zstd | 78351| 96| 2199| 204| 80| > + |-----------|--------|---------|----------|------|------| > + > + |-----------|--------|---------|----------|------|------| > + |4 Channels |Total |down |throughput| send | recv | > + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | > + |-----------|--------|---------|----------|------|------| > + |qatzip | 20336| 25| 8557| 110| 190| > + |-----------|--------|---------|----------|------|------| > + |zstd | 39324| 31| 4389| 406| 160| > + |-----------|--------|---------|----------|------|------| > + > + |-----------|--------|---------|----------|------|------| > + |8 Channels |Total |down |throughput| send | recv | > + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | > + |-----------|--------|---------|----------|------|------| > + |qatzip | 20208| 22| 8613| 125| 300| > + |-----------|--------|---------|----------|------|------| > + |zstd | 20515| 22| 8438| 800| 340| > + |-----------|--------|---------|----------|------|------| > + > +max-bandwidth: 10 GBps (Gbytes/sec) > + > +.. code-block:: text > + > + |-----------|--------|---------|----------|------|------| > + |2 Channels |Total |down |throughput| send | recv | > + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | > + |-----------|--------|---------|----------|------|------| > + |qatzip | 22450| 77| 7748| 80| 125| > + |-----------|--------|---------|----------|------|------| > + |zstd | 78339| 76| 2199| 204| 80| > + |-----------|--------|---------|----------|------|------| > + > + |-----------|--------|---------|----------|------|------| > + |4 Channels |Total |down |throughput| send | recv | > + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | > + |-----------|--------|---------|----------|------|------| > + |qatzip | 13017| 24| 13401| 180| 285| > + |-----------|--------|---------|----------|------|------| > + |zstd | 39466| 21| 4373| 406| 160| > + |-----------|--------|---------|----------|------|------| > + > + |-----------|--------|---------|----------|------|------| > + |8 Channels |Total |down |throughput| send | recv | > + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | > + |-----------|--------|---------|----------|------|------| > + |qatzip | 10255| 22| 17037| 280| 590| > + |-----------|--------|---------|----------|------|------| > + |zstd | 20126| 77| 8595| 810| 340| > + |-----------|--------|---------|----------|------|------| > + > +max-bandwidth: 1.25 GBps (Gbytes/sec) > + > +.. code-block:: text > + > + |-----------|--------|---------|----------|----------|------|------| > + |8 Channels |Total |down |throughput|pages per | send | recv | > + | |time(ms)|time(ms) |(mbps) |second | cpu %| cpu% | > + |-----------|--------|---------|----------|----------|------|------| > + |qatzip | 16630| 28| 10467| 2940235| 160| 360| > + |-----------|--------|---------|----------|----------|------|------| > + |zstd | 20165| 24| 8579| 2391465| 810| 340| > + |-----------|--------|---------|----------|----------|------|------| > + |none | 46063| 40| 10848| 330240| 45| 85| > + |-----------|--------|---------|----------|----------|------|------| > + > +If the user has enabled compression in live migration, using QAT can save > the > +host CPU resources. > + > +When compression is enabled, the bottleneck of migration is usually the > +compression throughput on the sender side, since CPU decompression > throughput > +is higher than compression, some reference data > +https://github.com/inikep/lzbench, so more CPU resources need to be > allocated > +to the sender side. > + > +Summary: > + > +1. In the 1GBps case, QAT only uses 88% CPU utilization to reach 1GBps, > but > + ZSTD needs 800%. > + > +2. In the 10Gbps case, QAT uses 180% CPU utilization to reach 10GBps. but > ZSTD > + still cannot reach 10Gbps even if it uses 810%. > + > +3. The QAT decompression CPU utilization is higher than compression and > ZSTD, > + because: > + > + a. When using QAT compression, the data needs to be copied to the QAT > memory > + (for DMA operations), and the same for decompression. However, > + do_user_addr_fault will be triggered during decompression because the > QAT > + decompressed data is copied to the VM address space for the first > time, in > + addition, both compression and decompression are processed by QAT and > do not > + consume CPU resources, so the CPU utilization of the receiver is > slightly > + higher than the sender. > + > + b. Since zstd decompression decompresses data directly into the VM > address > + space, there is one less memory copy than QAT, so the CPU utilization > on the > + receiver is better than QAT. For the 1GBps case, the receiver CPU > + utilization is 125%, and the memory copy occupies ~80% of CPU > utilization. > + > +How To Choose Between QATzip and QPL > +==================================== > +Starting from Intel 4th Gen Intel Xeon Scalable processors, codenamed > Sapphire > +Rapids processor(``SPR``), it supports multiple build-in accelerators > including > +``QAT`` and ``IAA``, the former can accelerate ``QATzip``, and the latter > is > +used to accelerate ``QPL``. > + > +Here are some suggestions: > + > +1 - If your live migration scenario is limited network bandwidth and > ``QAT`` > +hardware resources exceed ``IAA``, then use the ``QATzip`` method, which > +can save a lot of host CPU resources for compression. > + > +2 - If your system cannot support shared virtual memory(SVM) technology, > please > +use ``QATzip`` method because ``QPL`` performance is not good without SVM > +support. > + > +3 - For other scenarios, please use the ``QPL`` method first. > -- > Yichen Wang
On Tue, Jul 16, 2024 at 02:34:07AM +0000, Liu, Yuan1 wrote: > > -----Original Message----- > > From: Yichen Wang <yichen.wang@bytedance.com> > > Sent: Tuesday, July 16, 2024 6:13 AM > > To: Peter Xu <peterx@redhat.com>; Fabiano Rosas <farosas@suse.de>; Paolo > > Bonzini <pbonzini@redhat.com>; Daniel P. Berrangé <berrange@redhat.com>; > > Eduardo Habkost <eduardo@habkost.net>; Marc-André Lureau > > <marcandre.lureau@redhat.com>; Thomas Huth <thuth@redhat.com>; Philippe > > Mathieu-Daudé <philmd@linaro.org>; Eric Blake <eblake@redhat.com>; Markus > > Armbruster <armbru@redhat.com>; Laurent Vivier <lvivier@redhat.com>; qemu- > > devel@nongnu.org > > Cc: Hao Xiang <hao.xiang@linux.dev>; Liu, Yuan1 <yuan1.liu@intel.com>; > > Zou, Nanhai <nanhai.zou@intel.com>; Ho-Ren (Jack) Chuang > > <horenchuang@bytedance.com>; Wang, Yichen <yichen.wang@bytedance.com> > > Subject: [PATCH v6 1/5] docs/migration: add qatzip compression feature > > > > From: Yuan Liu <yuan1.liu@intel.com> > > > > add Intel QATzip compression method introduction > > > > Signed-off-by: Yuan Liu <yuan1.liu@intel.com> > > Reviewed-by: Nanhai Zou <nanhai.zou@intel.com> > > Reviewed-by: Peter Xu <peterx@redhat.com> > > Reviewed-by: Yichen Wang <yichen.wang@bytedance.com> > > --- > > docs/devel/migration/features.rst | 1 + > > docs/devel/migration/qatzip-compression.rst | 251 ++++++++++++++++++++ > > 2 files changed, 252 insertions(+) > > create mode 100644 docs/devel/migration/qatzip-compression.rst > > > > diff --git a/docs/devel/migration/features.rst > > b/docs/devel/migration/features.rst > > index 58f8fd9e16..8f431d52f9 100644 > > --- a/docs/devel/migration/features.rst > > +++ b/docs/devel/migration/features.rst > > @@ -14,3 +14,4 @@ Migration has plenty of features to support different > > use cases. > > CPR > > qpl-compression > > uadk-compression > > + qatzip-compression > > diff --git a/docs/devel/migration/qatzip-compression.rst > > b/docs/devel/migration/qatzip-compression.rst > > new file mode 100644 > > index 0000000000..72fa3e2826 > > --- /dev/null > > +++ b/docs/devel/migration/qatzip-compression.rst > > @@ -0,0 +1,251 @@ > > +================== > > +QATzip Compression > > +================== > > +In scenarios with limited network bandwidth, the ``QATzip`` solution can > > help > > +users save a lot of host CPU resources by accelerating compression and > > +decompression through the Intel QuickAssist Technology(``QAT``) hardware. > > Hi Yichen > > Thanks for adding the part of Performance Testing with QATzip, I wonder if we > can remove Performance Testing with QATzip part and directly add the following > content. > > Here, we use a typical example of limited bandwidth to illustrate the advantages > of QATzip. If the user is interested in qatzip, he still needs to verify the performance > by himself. > > +The following test was conducted using 8 multifd channels and 10Gbps network > +bandwidth. The results show that, compared to zstd, ``QATzip`` significantly > +saves CPU resources on the sender and reduces migration time. Compared to the > +uncompressed solution, ``QATzip`` greatly improves the dirty page processing > +capability, indicated by the Pages per Second metric, and also reduces the > +total migration time. > + > +:: > + > + VM Configuration: 16 vCPU and 64G memory > + VM Workload: all vCPUs are idle and 54G memory is filled with Silesia data. > + QAT Devices: 4 > + |-----------|--------|---------|----------|----------|------|------| > + |8 Channels |Total |down |throughput|pages per | send | recv | > + | |time(ms)|time(ms) |(mbps) |second | cpu %| cpu% | > + |-----------|--------|---------|----------|----------|------|------| > + |qatzip | 16630| 28| 10467| 2940235| 160| 360| > + |-----------|--------|---------|----------|----------|------|------| > + |zstd | 20165| 24| 8579| 2391465| 810| 340| > + |-----------|--------|---------|----------|----------|------|------| > + |none | 46063| 40| 10848| 330240| 45| 85| > + |-----------|--------|---------|----------|----------|------|------| Yes this looks much simpler and better. The 10GBps test isn't that useful at least, especially with nocomp numbers absent. I didn't say when looking previously, but it'll be better to clarify the numbers. Yuan, thanks so much for reviewing all the relevant patches. It's very helpful to us.
diff --git a/docs/devel/migration/features.rst b/docs/devel/migration/features.rst index 58f8fd9e16..8f431d52f9 100644 --- a/docs/devel/migration/features.rst +++ b/docs/devel/migration/features.rst @@ -14,3 +14,4 @@ Migration has plenty of features to support different use cases. CPR qpl-compression uadk-compression + qatzip-compression diff --git a/docs/devel/migration/qatzip-compression.rst b/docs/devel/migration/qatzip-compression.rst new file mode 100644 index 0000000000..72fa3e2826 --- /dev/null +++ b/docs/devel/migration/qatzip-compression.rst @@ -0,0 +1,251 @@ +================== +QATzip Compression +================== +In scenarios with limited network bandwidth, the ``QATzip`` solution can help +users save a lot of host CPU resources by accelerating compression and +decompression through the Intel QuickAssist Technology(``QAT``) hardware. + +``QATzip`` is a user space library which builds on top of the Intel QuickAssist +Technology user space library, to provide extended accelerated compression and +decompression services. + +For more ``QATzip`` introduction, please refer to `QATzip Introduction +<https://github.com/intel/QATzip?tab=readme-ov-file#introductionl>`_ + +QATzip Compression Framework +============================ + +:: + + +----------------+ + | MultiFd Thread | + +-------+--------+ + | + | compress/decompress + +-------+--------+ + | QATzip library | + +-------+--------+ + | + +-------+--------+ + | QAT library | + +-------+--------+ + | user space + --------+--------------------- + | kernel space + +------+-------+ + | QAT Driver | + +------+-------+ + | + +------+-------+ + | QAT Devices | + +--------------+ + + +QATzip Installation +------------------- + +The ``QATzip`` installation package has been integrated into some Linux +distributions and can be installed directly. For example, the Ubuntu Server +24.04 LTS system can be installed using below command + +.. code-block:: shell + + #apt search qatzip + libqatzip-dev/noble 1.2.0-0ubuntu3 amd64 + Intel QuickAssist user space library development files + + libqatzip3/noble 1.2.0-0ubuntu3 amd64 + Intel QuickAssist user space library + + qatzip/noble,now 1.2.0-0ubuntu3 amd64 [installed] + Compression user-space tool for Intel QuickAssist Technology + + #sudo apt install libqatzip-dev libqatzip3 qatzip + +If your system does not support the ``QATzip`` installation package, you can +use the source code to build and install, please refer to `QATzip source code installation +<https://github.com/intel/QATzip?tab=readme-ov-file#build-intel-quickassist-technology-driver>`_ + +QAT Hardware Deployment +----------------------- + +``QAT`` supports physical functions(PFs) and virtual functions(VFs) for +deployment, and users can configure ``QAT`` resources for migration according +to actual needs. For more details about ``QAT`` deployment, please refer to +`Intel QuickAssist Technology Documentation +<https://intel.github.io/quickassist/index.html>`_ + +For more ``QAT`` hardware introduction, please refer to `intel-quick-assist-technology-overview +<https://www.intel.com/content/www/us/en/architecture-and-technology/intel-quick-assist-technology-overview.html>`_ + +How To Use QATzip Compression +============================= + +1 - Install ``QATzip`` library + +2 - Build ``QEMU`` with ``--enable-qatzip`` parameter + + E.g. configure --target-list=x86_64-softmmu --enable-kvm ``--enable-qatzip`` + +3 - Set ``migrate_set_parameter multifd-compression qatzip`` + +4 - Set ``migrate_set_parameter multifd-qatzip-level comp_level``, the default +comp_level value is 1, and it supports levels from 1 to 9 + + +Performance Testing with QATzip +=============================== + +Testing environment is being set as below: + +VM configuration:16 vCPU, 64G memory; + +VM Workload: all vCPUs are idle and 54G memory is filled with Silesia data; + +QAT Devices: 4; + +Sender migration parameters: + +.. code-block:: shell + + migrate_set_capability multifd on + migrate_set_parameter multifd-channels 2/4/8 + migrate_set_parameter max-bandwidth 1G/10G + migrate_set_parameter multifd-compression qatzip/zstd + +Receiver migration parameters: + +.. code-block:: shell + + migrate_set_capability multifd on + migrate_set_parameter multifd-channels 2 + migrate_set_parameter multifd-compression qatzip/zstd + +max-bandwidth: 1 GBps (Gbytes/sec) + +.. code-block:: text + + |-----------|--------|---------|----------|------|------| + |2 Channels |Total |down |throughput| send | recv | + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | + |-----------|--------|---------|----------|------|------| + |qatzip | 21607| 77| 8051| 88| 125| + |-----------|--------|---------|----------|------|------| + |zstd | 78351| 96| 2199| 204| 80| + |-----------|--------|---------|----------|------|------| + + |-----------|--------|---------|----------|------|------| + |4 Channels |Total |down |throughput| send | recv | + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | + |-----------|--------|---------|----------|------|------| + |qatzip | 20336| 25| 8557| 110| 190| + |-----------|--------|---------|----------|------|------| + |zstd | 39324| 31| 4389| 406| 160| + |-----------|--------|---------|----------|------|------| + + |-----------|--------|---------|----------|------|------| + |8 Channels |Total |down |throughput| send | recv | + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | + |-----------|--------|---------|----------|------|------| + |qatzip | 20208| 22| 8613| 125| 300| + |-----------|--------|---------|----------|------|------| + |zstd | 20515| 22| 8438| 800| 340| + |-----------|--------|---------|----------|------|------| + +max-bandwidth: 10 GBps (Gbytes/sec) + +.. code-block:: text + + |-----------|--------|---------|----------|------|------| + |2 Channels |Total |down |throughput| send | recv | + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | + |-----------|--------|---------|----------|------|------| + |qatzip | 22450| 77| 7748| 80| 125| + |-----------|--------|---------|----------|------|------| + |zstd | 78339| 76| 2199| 204| 80| + |-----------|--------|---------|----------|------|------| + + |-----------|--------|---------|----------|------|------| + |4 Channels |Total |down |throughput| send | recv | + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | + |-----------|--------|---------|----------|------|------| + |qatzip | 13017| 24| 13401| 180| 285| + |-----------|--------|---------|----------|------|------| + |zstd | 39466| 21| 4373| 406| 160| + |-----------|--------|---------|----------|------|------| + + |-----------|--------|---------|----------|------|------| + |8 Channels |Total |down |throughput| send | recv | + | |time(ms)|time(ms) |(mbps) | cpu %| cpu% | + |-----------|--------|---------|----------|------|------| + |qatzip | 10255| 22| 17037| 280| 590| + |-----------|--------|---------|----------|------|------| + |zstd | 20126| 77| 8595| 810| 340| + |-----------|--------|---------|----------|------|------| + +max-bandwidth: 1.25 GBps (Gbytes/sec) + +.. code-block:: text + + |-----------|--------|---------|----------|----------|------|------| + |8 Channels |Total |down |throughput|pages per | send | recv | + | |time(ms)|time(ms) |(mbps) |second | cpu %| cpu% | + |-----------|--------|---------|----------|----------|------|------| + |qatzip | 16630| 28| 10467| 2940235| 160| 360| + |-----------|--------|---------|----------|----------|------|------| + |zstd | 20165| 24| 8579| 2391465| 810| 340| + |-----------|--------|---------|----------|----------|------|------| + |none | 46063| 40| 10848| 330240| 45| 85| + |-----------|--------|---------|----------|----------|------|------| + +If the user has enabled compression in live migration, using QAT can save the +host CPU resources. + +When compression is enabled, the bottleneck of migration is usually the +compression throughput on the sender side, since CPU decompression throughput +is higher than compression, some reference data +https://github.com/inikep/lzbench, so more CPU resources need to be allocated +to the sender side. + +Summary: + +1. In the 1GBps case, QAT only uses 88% CPU utilization to reach 1GBps, but + ZSTD needs 800%. + +2. In the 10Gbps case, QAT uses 180% CPU utilization to reach 10GBps. but ZSTD + still cannot reach 10Gbps even if it uses 810%. + +3. The QAT decompression CPU utilization is higher than compression and ZSTD, + because: + + a. When using QAT compression, the data needs to be copied to the QAT memory + (for DMA operations), and the same for decompression. However, + do_user_addr_fault will be triggered during decompression because the QAT + decompressed data is copied to the VM address space for the first time, in + addition, both compression and decompression are processed by QAT and do not + consume CPU resources, so the CPU utilization of the receiver is slightly + higher than the sender. + + b. Since zstd decompression decompresses data directly into the VM address + space, there is one less memory copy than QAT, so the CPU utilization on the + receiver is better than QAT. For the 1GBps case, the receiver CPU + utilization is 125%, and the memory copy occupies ~80% of CPU utilization. + +How To Choose Between QATzip and QPL +==================================== +Starting from Intel 4th Gen Intel Xeon Scalable processors, codenamed Sapphire +Rapids processor(``SPR``), it supports multiple build-in accelerators including +``QAT`` and ``IAA``, the former can accelerate ``QATzip``, and the latter is +used to accelerate ``QPL``. + +Here are some suggestions: + +1 - If your live migration scenario is limited network bandwidth and ``QAT`` +hardware resources exceed ``IAA``, then use the ``QATzip`` method, which +can save a lot of host CPU resources for compression. + +2 - If your system cannot support shared virtual memory(SVM) technology, please +use ``QATzip`` method because ``QPL`` performance is not good without SVM +support. + +3 - For other scenarios, please use the ``QPL`` method first.