Re: [Qemu-devel] dataplane performance on s390

[Fam Zheng]

On Mon, 06/09 15:43, Karl Rister wrote:
> Hi All
> 
> I was asked by our development team to do a performance sniff test of the
> latest dataplane code on s390 and compare it against qemu.git.  Here is a
> brief description of the configuration, the testing done, and then the
> results.
> 
> Configuration:
> 
> Host: 26 CPU LPAR, 64GB, 8 zFCP adapters
> Guest: 4 VCPU, 1GB, 128 virtio block devices
> 
> Each virtio block device maps to a dm-multipath device in the host with 8
> paths.  Multipath is configured with the service-time policy.  All block
> devices are configured to use the deadline IO scheduler.
> 
> Test:
> 
> FIO is used to run 4 scenarios: sequential read, sequential write, random
> read, and random write.  Sequential scenarios use a 128KB request size and
> random scenarios us a 8KB request size.  Each scenario is run with an
> increasing number of jobs, from 1 to 128 (powers of 2).  Each job is bound
> to an individual file on an ext3 file system on a virtio device and uses
> O_DIRECT, libaio, and iodepth=1.  Each test is run three times for 2 minutes
> each, the first iteration (a warmup) is thrown out and the next two
> iterations are averaged together.
> 
> Results:
> 
> Baseline: qemu.git 93f94f9018229f146ed6bbe9e5ff72d67e4bd7ab
> 
> Dataplane: bdrv_set_aio_context 0ab50cde71aa27f39b8a3ea4766ff82671adb2a4

Hi Karl,

Thanks for the results.

The throughput differences look minimal, where is the bandwidth saturated in
these tests?  And why use iodepth=1, not more?

Thanks,
Fam

> 
> Sequential Read:
> 
> Overall a slight throughput regression with a noticeable reduction in CPU
> efficiency.
> 
> 1 Job: Throughput regressed -1.4%, CPU improved -0.83%.
> 2 Job: Throughput regressed -2.5%, CPU regressed +2.81%
> 4 Job: Throughput regressed -2.2%, CPU regressed +12.22%
> 8 Job: Throughput regressed -0.7%, CPU regressed +9.77%
> 16 Job: Throughput regressed -3.4%, CPU regressed +7.04%
> 32 Job: Throughput regressed -1.8%, CPU regressed +12.03%
> 64 Job: Throughput regressed -0.1%, CPU regressed +10.60%
> 128 Job: Throughput increased +0.3%, CPU regressed +10.70%
> 
> Sequential Write:
> 
> Mostly regressed throughput, although it gets better as job count increases
> and even has some gains at higher job counts.  CPU efficiency is regressed.
> 
> 1 Job: Throughput regressed -1.9%, CPU regressed +0.90%
> 2 Job: Throughput regressed -2.0%, CPU regressed +1.07%
> 4 Job: Throughput regressed -2.4%, CPU regressed +8.68%
> 8 Job: Throughput regressed -2.0%, CPU regressed +4.23%
> 16 Job: Throughput regressed -5.0%, CPU regressed +10.53%
> 32 Job: Throughput improved +7.6%, CPU regressed +7.37%
> 64 Job: Throughput regressed -0.6%, CPU regressed +7.29%
> 128 Job: Throughput improved +8.3%, CPU regressed +6.68%
> 
> Random Read:
> 
> Again, mostly throughput regressions except for the largest job counts.  CPU
> efficiency is regressed at all data points.
> 
> 1 Job: Throughput regressed -3.0%, CPU regressed +0.14%
> 2 Job: Throughput regressed -3.6%, CPU regressed +6.86%
> 4 Job: Throughput regressed -5.1%, CPU regressed +11.11%
> 8 Job: Throughput regressed -8.6%, CPU regressed +12.32%
> 16 Job: Throughput regressed -5.7%, CPU regressed +12.99%
> 32 Job: Throughput regressed -7.4%, CPU regressed +7.62%
> 64 Job: Throughput improved +10.0%, CPU regressed +10.83%
> 128 Job: Throughput improved +10.7%, CPU regressed +10.85%
> 
> Random Write:
> 
> Throughput and CPU regressed at all but one data point.
> 
> 1 Job: Throughput regressed -2.3%, CPU improved -1.50%
> 2 Job: Throughput regressed -2.2%, CPU regressed +0.16%
> 4 Job: Throughput regressed -1.0%, CPU regressed +8.36%
> 8 Job: Throughput regressed -8.6%, CPU regressed +12.47%
> 16 Job: Throughput regressed -3.1%, CPU regressed +12.40%
> 32 Job: Throughput regressed -0.2%, CPU regressed +11.59%
> 64 Job: Throughput regressed -1.9%, CPU regressed +12.65%
> 128 Job: Throughput improved +5.6%, CPU regressed +11.68%
> 
> 
> * CPU consumption is an efficiency calculation of usage per MB of
> throughput.
> 
> -- 
> Karl Rister <address@hidden>
> IBM Linux/KVM Development Optimization
> 
>