dirtop(8) System Manager's Manual dirtop(8)
NAME
dirtop - File reads and writes by directory. Top for directories.
SYNOPSIS
dirtop -d directory1,directory2,... [-h] [-C] [-r MAXROWS] [-s
{reads,writes,rbytes,wbytes}] [-p PID] [interval] [count]
DESCRIPTION
This is top for directories.
This traces file reads and writes, and prints a per-directory summary
every interval (by default, 1 second). By default the summary is sorted
on the highest read throughput (Kbytes). Sorting order can be changed
via -s option.
This uses in-kernel eBPF maps to store per process summaries for effi-
ciency.
This script works by tracing the __vfs_read() and __vfs_write() func-
tions using kernel dynamic tracing, which instruments explicit read and
write calls. If files are read or written using another means (eg, via
mmap()), then they will not be visible using this tool. Also, this tool
will need updating to match any code changes to those vfs functions.
This should be useful for file system workload characterization when
analyzing the performance of applications.
Note that tracing VFS level reads and writes can be a frequent activ-
ity, and this tool can begin to cost measurable overhead at high I/O
rates.
Since this uses BPF, only the root user can use this tool.
REQUIREMENTS
CONFIG_BPF and bcc.
OPTIONS
-d Defines a list of directories, comma separated, to observe.
Wildcards are allowed if between single bracket.
-C Don't clear the screen.
-r MAXROWS
Maximum number of rows to print. Default is 20.
-s {reads,writes,rbytes,wbytes}
Sort column. Default is rbytes (read throughput).
-p PID Trace this PID only.
interval
Interval between updates, seconds.
count Number of interval summaries.
EXAMPLES
Summarize block device I/O by directory, 1 second screen refresh:
# dirtop -d '/hdfs/uuid/*/yarn'
Don't clear the screen, and top 8 rows only:
# dirtop -d '/hdfs/uuid/*/yarn' -Cr 8
5 second summaries, 10 times only:
# dirtop -d '/hdfs/uuid/*/yarn' 5 10
Report read & write IOs generated in mutliple yarn and data directo-
ries:
# dirtop -d '/hdfs/uuid/*/yarn,/hdfs/uuid/*/data'
FIELDS
loadavg:
The contents of /proc/loadavg
READS Count of reads during interval.
WRITES Count of writes during interval.
R_Kb Total read Kbytes during interval.
W_Kb Total write Kbytes during interval.
PATH The path were the IOs were accounted.
OVERHEAD
Depending on the frequency of application reads and writes, overhead
can become significant, in the worst case slowing applications by over
50%. Hopefully for real world workloads the overhead is much less --
test before use. The reason for the high overhead is that VFS reads and
writes can be a frequent event, and despite the eBPF overhead being
very small per event, if you multiply this small overhead by a million
events per second, it becomes a million times worse. Literally. You can
gauge the number of reads and writes using the vfsstat(8) tool, also
from bcc.
SOURCE
This is from bcc.
https://github.com/iovisor/bcc
Also look in the bcc distribution for a companion _examples.txt file
containing example usage, output, and commentary for this tool.
OS
Linux
STABILITY
Unstable - in development.
AUTHOR
Erwan Velu
INSPIRATION
filetop(8) by Brendan Gregg
SEE ALSO
vfsstat(8), vfscount(8), fileslower(8)
USER COMMANDS 2020-03-16 dirtop(8)
Generated by dwww version 1.16 on Tue Dec 16 17:17:12 CET 2025.