Eidetic Systems
This newspaper appeared inward OSDI'14. The authors are all from University of Michigan: David Devecsery, Michael Chow, Xianzheng Dou, Jason Flinn, too Peter M. Chen.
This newspaper presents a transformative systems work, inward that it introduces a practical eidetic arrangement implementation on a Linux computer/workstation. This newspaper is a tour de force: It undertakes a huge implementation endeavor to implement a really useful too novel eidetic memory/system service. The authors should last commended for their audaciousness.
An eidetic estimator arrangement tin cry back whatever past times nation that existed on that computer, including all versions of all files, the retentiveness too register nation of processes, interprocess communication, too network input. An eidetic estimator arrangement tin explicate the lineage of each byte of electrical flow too past times state. (This is related to the concept of information provenance, which I nurture briefly at the cease of my review.)
Another utilization illustration for an eidetic arrangement is to attain postmortem of a hack assault too whether it leaked whatever of import information. In the evaluation section, the newspaper uses equally merely about other illustration report the heartbleed attack, which occurred during fourth dimension the authors were testing/evaluating their eidetic arrangement implementation.
With a proficient GUI for querying, the eidetic arrangement concept tin heighten the Mac OSX Time Machine significantly, amongst information lineage/provenance, backward querying, too frontwards querying/correction. This tin augment fourth dimension go amongst analytics, too yous tin have got a fourth dimension automobile on steroids. (Accomplishment unlocked: +100 points for serious utilization of fourth dimension automobile too fourth dimension go inward writing.)
Arnold records fifty-fifty user propagated lineage, such equally a user reading a webpage too entering text into an editor equally a result. (Of course of report this leads to introducing merely about fake positives, equally it needs to last done speculatively.) Tracking this genuinely required a lot of work: "Understanding GUI output turned out to last tricky, however, because most programs nosotros looked at did non shipping text to the X server, but instead sent binary glyphs generated past times translating the output characters into a special font. Arnold identifies these glyphs equally they are passed to criterion X too graphical library functions. It traces the lineage backward from these glyphs using i of the higher upwards linkages (e.g., the index linkage)."
Finally, for the querying of Arnold, the newspaper has this to say. "A backward interrogation proceeds inward a tree-like search, fanning out from i or to a greater extent than target states. The search continues until it is stopped past times the user or all nation has been traced dorsum to external arrangement inputs. As the search fans out, Arnold replays multiple replay groups inward parallel. In addition, if no lineage is specified, it may examination multiple linkages for the same grouping inward parallel, terminating less restrictive searches if a to a greater extent than restrictive search finds a linkage."
Unfortunately, user-friendly GUI-based tools for querying is non available yet. That would last cry for likewise much from this newspaper which already packed a lot of contributions into a unmarried publication. The evaluation department gives merely about results most backward too frontwards querying performance inward Arnold.
A remaining kink for a distributed eidetic arrangement could last the toll of querying. Querying too replay is already tiresome too difficult for a unmarried eidetic system, too it is probable to go to a greater extent than complicated for a distributed arrangement since coordination of replay is needed across the machines involved inward the replay.
This newspaper presents a transformative systems work, inward that it introduces a practical eidetic arrangement implementation on a Linux computer/workstation. This newspaper is a tour de force: It undertakes a huge implementation endeavor to implement a really useful too novel eidetic memory/system service. The authors should last commended for their audaciousness.
An eidetic estimator arrangement tin cry back whatever past times nation that existed on that computer, including all versions of all files, the retentiveness too register nation of processes, interprocess communication, too network input. An eidetic estimator arrangement tin explicate the lineage of each byte of electrical flow too past times state. (This is related to the concept of information provenance, which I nurture briefly at the cease of my review.)
Motivation
One utilization illustration for an eidetic arrangement is to rail where/how erroneous information entered to the system. The newspaper considers tracking downwards a faulty bibtex reference equally a illustration study. This is done using a backwards query. After tracking downwards the faulty bibtex reference yous tin too therefore perform a frontwards interrogation on the eidetic system, inward lodge to figure out which documents are contaminated amongst this faulty information too to laid them.Another utilization illustration for an eidetic arrangement is to attain postmortem of a hack assault too whether it leaked whatever of import information. In the evaluation section, the newspaper uses equally merely about other illustration report the heartbleed attack, which occurred during fourth dimension the authors were testing/evaluating their eidetic arrangement implementation.
With a proficient GUI for querying, the eidetic arrangement concept tin heighten the Mac OSX Time Machine significantly, amongst information lineage/provenance, backward querying, too frontwards querying/correction. This tin augment fourth dimension go amongst analytics, too yous tin have got a fourth dimension automobile on steroids. (Accomplishment unlocked: +100 points for serious utilization of fourth dimension automobile too fourth dimension go inward writing.)
Design too implementation
The authors educate the eidetic system, Arnold, past times modifying Linux core to tape all nondeterministic information that enters a process: the order, render values, too retentiveness addresses modified past times a arrangement call, the timing too values of received signals, too the results of querying the arrangement time. Arnold too accompanying eidetic arrangement tools (for replay, etc.) are available equally opensource.The cardinal technologies that enable Arnold to render the properties of an eidetic arrangement efficiently are deterministic tape too replay, model-based compression, deduplicated file recording, operating arrangement tracking of information menses betwixt processes, too retrospective binary analysis of information menses inside processes.Arnold uses deterministic tape too replay, too trades storage for recomputation whenever possible. That is, Arnold alone saves nondeterministic choices or novel input too tin reproduce everything else past times recomputation. The major infinite saving technique Arnold uses is model based compression: Arnold constructs a model for predictable operations too records alone instances inward which the returned information differs from the model. Another optimization is re-create on RAW (read-after-write) recording: "To deduplicate the read file data, Arnold saves a version of a file alone on the showtime read afterward the file is written. Subsequent reads log alone a reference to the saved version, along amongst the read offset too render code." These techniques enable Arnold to agree four years of desktop/workstation eidetic arrangement into 4TB of off-the-shelf difficult disk (which costs $150).
Querying too Replaying
Arnold uses the replay groups abstraction to perform storing too replaying efficiently. Replay groups consist of oftentimes communicating processes which tin last replayed independently of whatever other group. Arnold employs "Pin" binary instrumentation to analyze replayed executions too rail the lineage of information inside a replay group. Inter procedure communication is tracked amongst the assistance of a dependency graph which keeps rail of the communications betwixt unlike replay groups. Bundling oftentimes communicating processes into a grouping ensures that a large seat out of conversations demand non last recorded to the dependency graph. As such selection of replay grouping (and replay grouping size) gives ascent to a tradeoff betwixt storage efficiency too interrogation efficiency. It would last overnice if the newspaper provided the replay groups it used inward Arnold equally a table. This information would last useful to empathize the replay groups concept better.Arnold records fifty-fifty user propagated lineage, such equally a user reading a webpage too entering text into an editor equally a result. (Of course of report this leads to introducing merely about fake positives, equally it needs to last done speculatively.) Tracking this genuinely required a lot of work: "Understanding GUI output turned out to last tricky, however, because most programs nosotros looked at did non shipping text to the X server, but instead sent binary glyphs generated past times translating the output characters into a special font. Arnold identifies these glyphs equally they are passed to criterion X too graphical library functions. It traces the lineage backward from these glyphs using i of the higher upwards linkages (e.g., the index linkage)."
Finally, for the querying of Arnold, the newspaper has this to say. "A backward interrogation proceeds inward a tree-like search, fanning out from i or to a greater extent than target states. The search continues until it is stopped past times the user or all nation has been traced dorsum to external arrangement inputs. As the search fans out, Arnold replays multiple replay groups inward parallel. In addition, if no lineage is specified, it may examination multiple linkages for the same grouping inward parallel, terminating less restrictive searches if a to a greater extent than restrictive search finds a linkage."
Unfortunately, user-friendly GUI-based tools for querying is non available yet. That would last cry for likewise much from this newspaper which already packed a lot of contributions into a unmarried publication. The evaluation department gives merely about results most backward too frontwards querying performance inward Arnold.
Related piece of work on information provenance
Data provenance is a theme which has been studied equally constituent of the database plain traditionally. However, recent piece of work on information provenance started considering the work of capturing provenance for applications performing arbitrary computations (not resricted to a small-scale laid of valid transformations inward database systems). The newspaper "A primer on provenance" provides a overnice accessible survey of information provenance work.Future work
This newspaper presents an eidetic arrangement on a unmarried computer. An obvious hereafter direction is to enable edifice an eidetic distributed system. By leveraging Arnold, such a arrangement also seems to last inward attain now. Our piece of work on hybrid logical clocks tin also assistance hither past times relating too efficiently tracking causality across distributed nodes running Arnold. Since our hybrid logical clocks tin piece of work amongst loosely synchronized fourth dimension (a la NTP), too is resilient to doubt (it enables efficient tracking of causality without blocking for synchronization uncertainties), it tin last adopted for implementing a distributed eidetic arrangement inward practice.A remaining kink for a distributed eidetic arrangement could last the toll of querying. Querying too replay is already tiresome too difficult for a unmarried eidetic system, too it is probable to go to a greater extent than complicated for a distributed arrangement since coordination of replay is needed across the machines involved inward the replay.
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