|drsnoop(8)||System Manager's Manual||drsnoop(8)|
drsnoop - Trace direct reclaim events. Uses Linux eBPF/bcc.
drsnoop.py [-h] [-T] [-U] [-p PID] [-t TID] [-u UID] [-d DURATION] [-n name] [-v]
drsnoop trace direct reclaim events, showing which processes are allocing pages with direct reclaiming. This can be useful for discovering when allocstall (/p- roc/vmstat) continues to increase, whether it is caused by some critical proc- esses or not.
This works by tracing the direct reclaim events using kernel tracepoints.
This makes use of a Linux 4.4 feature (bpf_perf_event_output()); for kernels older than 4.4, see the version under tools/old, which uses an older mechanism.
Since this uses BPF, only the root user can use this tool.
CONFIG_BPF and bcc.
- Print usage message.
- Include a timestamp column.
- Show UID.
- -p PID
- Trace this process ID only (filtered in-kernel).
- -t TID
- Trace this thread ID only (filtered in-kernel).
- -u UID
- Trace this UID only (filtered in-kernel).
- -d DURATION
- Total duration of trace in seconds.
- -n name
- Only print processes where its name partially matches 'name' -v verbose Run in verbose mode. Will output system memory state
- Trace all direct reclaim events:
- # drsnoop
- Trace all direct reclaim events, for 10 seconds only:
- # drsnoop -d 10
- Trace all direct reclaim events, and include timestamps:
- # drsnoop -T
- Show UID:
- # drsnoop -U
- Trace PID 181 only:
- # drsnoop -p 181
- Trace UID 1000 only:
- # drsnoop -u 1000
- Trace all direct reclaim events from processes where its name partially match-
- es 'mond': # drnsnoop -n mond
This traces the kernel direct reclaim tracepoints and prints output for each event. As the rate of this is generally expected to be low (< 1000/s), the overhead is also expected to be negligible.
This is from bcc.
Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.
Unstable - in development.