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jabley : filesystem   40

EIO: Error Handling is Occasionally Correct
The reliability of file systems depends in part on how
well they propagate errors. We develop a static analysis technique, EDP, that analyzes how file systems and
storage device drivers propagate error codes. Running
our EDP analysis on all file systems and 3 major storage
device drivers in Linux 2.6, we find that errors are often
incorrectly propagated; 1153 calls (13%) drop an error
code without handling it.
We perform a set of analyses to rank the robustness
of each subsystem based on the completeness of its error propagation; we find that many popular file systems
are less robust than other available choices. We confirm that write errors are neglected more often than read
errors. We also find that many violations are not cornercase mistakes, but perhaps intentional choices. Finally,
we show that inter-module calls play a part in incorrect
error propagation, but that chained propagations do not.
In conclusion, error propagation appears complex and
hard to perform correctly in modern systems.
filetype:pdf  paper  comp-sci  filesystem  errors  correctness  error-handling 
march 2019 by jabley
Understanding Manycore Scalability of File Systems
We analyze the manycore scalability of five widelydeployed
file systems, namely, ext4, XFS, btrfs, F2FS,
and tmpfs, by using our open source benchmark suite,
FXMARK. FXMARK implements 19 microbenchmarks
to stress specific components of each file system and
includes three application benchmarks to measure the
macroscopic scalability behavior. We observe that file
systems are hidden scalability bottlenecks in many I/Ointensive
applications even when there is no apparent
contention at the application level. We found 25 scalability
bottlenecks in file systems, many of which are
unexpected or counterintuitive. We draw a set of observations
on file system scalability behavior and unveil several
core aspects of file system design that systems researchers
must address.
filetype:pdf  paper  filesystem  unix  performance  multi-core  modern  2016  btrfs  ext4  xfs 
november 2016 by jabley

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