|
The ADvanced Systems Laboratory (ADSL)
Overview
|
Gray-box Systems One of our earliest ideas was that of
building gray-box systems. The driving force behind this idea
is that in some scenarios it is challenging to change an existing
system to have the exact functionality desired; surprisingly, however,
in many cases it is still possible to realize the desired
functionality without any change to said system, through a combination
of measurement of the system plus knowledge (perhaps imperfect) of how
the system operates. This ``gray box'' knowledge thus formed the
center of the following line of research:
- Information and Control in Gray-Box Systems (SOSP '01).
Our original paper on the idea, and also the first SOSP paper from
our group. We describe the fundamental approach, and
highlight how it can be applied with three detailed case studies,
substantially improving performance of both microbenchmarks and real
applications.
- Exploiting Gray-Box Knowledge of Buffer-Cache Contents (USENIX '02).
We delve deeper into the idea that the
page-replacement algorithms of an operating system can be understood through
careful measurement, and build a novel tool (Dust) that fingerprints
existing operating systems and determines how they perform replacement. We
build a ``cache aware'' web server,
improving performance significantly through gray-box replacement knowledge.
- Controlling your PLACE in the File System with Gray-box
Techniques (USENIX '03). We build a layer on top of a file
system that enables applications to exert control over which files
are placed near one another, and which ones far apart. The paper
then shows how to utilize this control to improve web-server
performance as well as build an improved file-system benchmarking
tool.
- Roobust, Portable I/O Scheduling with the Disk Mimic
(USENIX'03). We show how detailed measurement of a
storage device can be used to build an entirely empirical model of its
behavior, which can then be used to develop a measurement-driven
disk scheduler. Our I/O scheduler outperforms classical heuristic
schedulers (such as C-LOOK or SSTF) substantially.
- Transforming Policies into Mechanisms with Infokernel
(SOSP '03) We take the gray-box approach to an extreme,
developing a new kernel (the infokernel) which exposes more detailed
information to applications, thus enabling more nuanced control of
system behavior. For example, by showing applications which pages in
memory are likely to soon be replaced and which are firmly
entrenched in memory, applications can adjust their behavior to
better exploit in-memory pages while also exerting influence over
page-replacement decisions. Four cases studies (in memory
management, file placement, I/O scheduling, and networking) show
considerable performance improvements can be realized as a result.
- Deploying Safe User-Level Network Services with icTCP (OSDI
'04). One last pure gray-box paper focuses just on
the networking stack. By exposing certain key pieces of TCP state
information, and providing (safely) control over a few key variables, we
show how many TCP extensions that previously required kernel modification
can be safely and efficiently realized at kernel level.
|
| |
|