* Chuan Zheng (zhengch...@huawei.com) wrote:
> From: Zheng Chuan <zhengch...@huawei.com>
Hi,
> Sometimes it is neccessary to evaluate dirty page rate before migration.
> Users could decide whether to proceed migration based on the evaluation
> in case of vm performance loss due to heavy workload.
> Unlikey simulating dirtylog sync which could do harm on runnning vm,
> we provide a sample-hash method to compare hash results for samping page.
> In this way, it would have hardly no impact on vm performance.
>
> We evaluate the dirtypage rate on running vm.
> The VM specifications for migration are as follows:
> - VM use 4-K page;
> - the number of VCPU is 32;
> - the total memory is 32Gigabit;
> - use 'mempress' tool to pressurize VM(mempress 4096 1024);
>
> ++++++++++++++++++++++++++++++++++++++++++
> | | dirtyrate |
> ++++++++++++++++++++++++++++++++++++++++++
> | no mempress | 4MB/s |
> ------------------------------------------
> | mempress 4096 1024 | 1204MB/s |
> ++++++++++++++++++++++++++++++++++++++++++
> | mempress 4096 4096 | 4000Mb/s |
> ++++++++++++++++++++++++++++++++++++++++++
This is quite neat; I know we've got other people who have asked
for a similar feature!
Have you tried to validate these numbers against a real migration - e.g.
try setting mempress to dirty just under 1GByte/s and see if you can
migrate it over a 10Gbps link?
Dave
> Test dirtyrate by qmp command like this:
> 1. virsh qemu-monitor-command [vmname] '{"execute":"cal_dirty_rate",
> "arguments": {"value": [sampletime]}}'
> 2. virsh qemu-monitor-command [vmname] '{"execute":"get_dirty_rate"}'
>
> Further test dirtyrate by libvirt api like this:
> virsh getdirtyrate [vmname] [sampletime]
>
> Zheng Chuan (8):
> migration/dirtyrate: Add get_dirtyrate_thread() function
> migration/dirtyrate: Add block_dirty_info to store dirtypage info
> migration/dirtyrate: Add dirtyrate statistics series functions
> migration/dirtyrate: Record hash results for each ramblock
> migration/dirtyrate: Compare hash results for recorded ramblock
> migration/dirtyrate: Implement get_sample_gap_period() and
> block_sample_gap_period()
> migration/dirtyrate: Implement calculate_dirtyrate() function
> migration/dirtyrate: Implement
> qmp_cal_dirty_rate()/qmp_get_dirty_rate() function
>
> migration/Makefile.objs | 1 +
> migration/dirtyrate.c | 424
> ++++++++++++++++++++++++++++++++++++++++++++++++
> migration/dirtyrate.h | 67 ++++++++
> qapi/migration.json | 24 +++
> qapi/pragma.json | 3 +-
> 5 files changed, 518 insertions(+), 1 deletion(-)
> create mode 100644 migration/dirtyrate.c
> create mode 100644 migration/dirtyrate.h
>
> --
> 1.8.3.1
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
