I am a Postdoctoral Researcher at the Department of Computer Science and Engineering at the University of Ioannina in Greece.
I am Giorgos E. Kappes from Ioannina, Greece and, currently,
I am a Postdoctoral Researcher at the Computer Systems Lab (CSL)
of the University of Ioannina. I am also a co-founder of
Polytropo Systems.
I have extensive experience
in conducting research in Computer Systems. My research includes the design, development, and
evaluation of system software for multi-tenant cloud environments. My research interests
include operating systems, computer architecture, data storage, and systems security.
I am also an expert in deployment and administration of enterprise-level IT infrastructure with over ten
years of hands-on experience.
I hold a PhD in Computer Science, an MSc in Computer Systems, and a BSc degree from the
Department of Computer Science and Engineering,
I completed my PhD and MSc under the supervision of
Prof. Stergios Anastasiadis.
In our research we studied approaches for efficient, effective, and secure support of multitenancy in
the datacenters of modern cloud environments.
For more information about me, you can
find my short resume in English, or my extensive
corriculum vitae in Greek, and
English.
You can also check my
github, and
gitlab profiles for a list of open source
projects that I've contributed on.
Polytropo Systems is a deep-tech startup spun out of the University of Ioannina, developing cutting-edge systems software that boosts the serving capacity of cloud infrastructures for data-intensive applications.
From Research to Real-World. Our technology originated in academic research and was officially approved as a university spin-off by the Governing Council of the University of Ioannina. Our innovation has been published in top-tier peer-reviewed venues and patented in the United States, with the University holding 30% of ownership.
Isolation and Performance: The Holy Grail of Cloud Computing. Commercial applications typically run on computing facilities consisting of numerous machines privately owned by a company or offered as public service by a cloud provider. The computing cost is lowered with an infrastructure that is shared across multiple applications to improve the hardware utilization and reduce the capital and operation expenditure. The existing resource virtualization techniques either introduce overheads that reduce the system capacity or limit the performance and security isolation among competing tenants. Also, the operating system causes excessive delays in data-intensive applications, which reduces the user-perceived performance.
Solution and Product. Our core product is Diciclo, a systems framework that redefines how tenants interact with I/O services in shared computing inrastructures. Unlike traditional architectures, Diciclo relocates critical system services outside the operating system, offering stronger performance and security isolation between tenants, reduced overheads from virtualization, improved throughput and latency under high utilization. The Diciclo framework intercepts the requests of application to I/O services (e.g., the filesystem) and transfers them to system services running outside the operating system. Our solution permits both the efficient transfer of the control and data traffic from the application to the services at user level and the execution of the services at user level. Our framework permits each tenant of a shared infrastructure to run its own services on each machine and be isolated from the other tenants. Additionally, the framework enables each tenant to rely less on the operating system and as a result to be less vulnerable to potential attacks or software bugs of the shared system software. We have experimentally shown that our technology improves substantially the utilization of the hardware resources that run data-intensive applications in cloud infrastructures. Thus, a business can reduce the capital investment and operation costs to serve a number of users. As a result, a business can become more competitive and offer better prices for its products to a broad user base consisting of business customers or individuals. Our technique affects a wide range of applications across several industries that critically rely on computing to serve their users. Our product consists of systems software and configuration that our customers run between the unmodified applications and the existing data storage infrastructure.
Innovation and Scalability. We develop innovative systems software that improves the efficiency of the IT infrastructures with direct benefit to the capital and operation expenditure of our customers. It also allows cloud providers and system vendors to offer products that require fewer hardware resources for a particular capacity of users or applications. Thus, they improve their competitiveness and offer products or services at lower costs. Our unique value proposition is the offering of systems software that our customers run between the applications and the storage infrastructure to achieve efficiency, performance and security. Our product is compatible with existing standard system interfaces and complements the products of data storage vendors. We do not replace the existing storage systems but enhance them with efficient client software at the application side. We foresee the industry to remain cost-sensitive for the upcoming years due to the potential geopolitical risks and inflation surge. Our product can address the rising cost of the IT infrastructure by improving the operation efficiency and reducing the overheads from the virtualization software or the operating system. Additionally, it improves the performance and security stability by serving the tenants through private system services.
Elevate Greece. We are happy to announce that Polytropo Systems is part of Elevate Greece. Elevate Greece is an initiative launched by the Greek Government, intended to identify promising startups and support their growth nurturing a robust innovation ecosystem along the way. You may find our profile in the Startup registry of Elevate Greece here.
My main research interests lie in the fields of operating systems, computer architecture, data storage, and systems security. However, I am interested in pretty much everything to do with computer systems. Following are some of the projects that I have worked on:
User-level Services for Multitenant Isolation.
The focus of this project is to enable multiple tenants to efficiently and
securely share the computing, storage, and network infrastructure of the datacenter and
reduce the conention for shared resources.
To this end, we take the radical approach of moving the data-intensive I/O
services at user level from the shared kernel, in order to serve the containers of
competing tenants over the same cloud machines. Our contributions consist of innovative
methods to handle POSIX-like system calls at user level through a library, the
producer-consumer transfer of data and requests over shared memory with efficient memory
copy and relaxed lock-free queues, the construction of stacked user-level I/O services,
and a multitenant access control mechanism built natively into a distributed filesystem.
Relaxed Concurrent Queues. The producer-consumer communication over shared memory is a critical function of current scalable systems. Queues that provide low latency and high throughput on highly utilized systems can improve the overall performance perceived by the end users. In order to address this demand, we set as priority to achieve both high operation performance and item transfer speed. The Relaxed Concurrent Queues (RCQs) are a family of queues that we have designed and implemented for that purpose. Our key idea is a relaxed ordering model that splits the enqueue and dequeue operations into a stage of sequential assignment to a queue slot and a stage of concurrent execution across the slots. At each slot, we apply no order restrictions among the operations of the same type. We experimentally show that our algorithms achieve factors to orders of magnitude advantage over the state-of-the-art strict or relaxed queue algorithms.
Optimized memory copy. Critical operations are often implemented in roughly the same way across multiple platforms, but differently by software systems running on the same platform. This observation is arguably justified by the potential restrictions of each software system, but it is surprising given the operation sensitivity to numerous platform-specific software and hardware parameters. With initial focus on the memory copy operation (memcpy), we introduce a methodology based on exhaustive search to optimize the performance across different platforms. We design and implement the Asterope algorithm to experimentally generate optimal memcpy parameters for two x86-64 processor models from different vendors. With experiments on microbenchmarks and two production systems, we demonstrate that Asterope respectively achieves up to 2.4x and 1.9x higher function and system performance in comparison to using the Linux kernel memcpy.
Multitenant Access Control.
Secure access control is a challenging problem that organizations face in
collaborative virtual environments, which has prevented many of them from migrating
critical data or applications into these environments. In our research we examined
approaches for efficient and effective support of multitenancy in filesystems used
in cloud environments. We introduced a system architecture that is backwards compatible to
object-based filesystems, and combines native access control with namespace isolation.
Our architecture securely isolates dfferent tenants, and enables flexible file sharing both
within and among tenants. We developed a Linux-based prototype solution over Ceph and
obtained encouraging experimental results about the scalability and low overhead of
our design on a local cluster and on Amazon AWS.
Most likely you will find me at A34 office in the first floor of the department. If not, below is more information on how you can reach me.
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