FM / lwtools

/usr/share/systemtap/examples/lwtools

Name	Size	Mode	Actions
accept2close-nd.8	1424	0644	edit dl rm
accept2close-nd.meta	597	0644	edit dl rm
accept2close-nd.stp	1798	0755	edit dl rm
accept2close-nd.txt	3385	0644	edit dl rm
biolatency-nd.8	1671	0644	edit dl rm
biolatency-nd.meta	622	0644	edit dl rm
biolatency-nd.stp	2071	0755	edit dl rm
biolatency-nd_example.txt	7362	0644	edit dl rm
bitesize-nd.8	1157	0644	edit dl rm
bitesize-nd.meta	491	0644	edit dl rm
bitesize-nd.stp	1543	0755	edit dl rm
bitesize-nd_example.txt	3426	0644	edit dl rm
execsnoop-nd.8	1235	0644	edit dl rm
execsnoop-nd.meta	570	0644	edit dl rm
execsnoop-nd.stp	1283	0755	edit dl rm
execsnoop-nd_example.txt	2585	0644	edit dl rm
fslatency-nd.8	1930	0644	edit dl rm
fslatency-nd.meta	660	0644	edit dl rm
fslatency-nd.stp	3982	0755	edit dl rm
fslatency-nd_example.txt	13384	0644	edit dl rm
fsslower-nd.8	1753	0644	edit dl rm
fsslower-nd.meta	623	0644	edit dl rm
fsslower-nd.stp	3715	0755	edit dl rm
fsslower-nd_example.txt	1938	0644	edit dl rm
killsnoop-nd.8	1131	0644	edit dl rm
killsnoop-nd.meta	384	0644	edit dl rm
killsnoop-nd.stp	1281	0755	edit dl rm
killsnoop-nd_example.txt	1908	0644	edit dl rm
opensnoop-nd.8	1268	0644	edit dl rm
opensnoop-nd.meta	357	0644	edit dl rm
opensnoop-nd.stp	1026	0755	edit dl rm
opensnoop-nd_example.txt	1124	0644	edit dl rm
README	107	0644	edit dl rm
rwtime-nd.8	1146	0644	edit dl rm
rwtime-nd.meta	412	0644	edit dl rm
rwtime-nd.stp	1599	0755	edit dl rm
rwtime-nd_example.txt	4185	0644	edit dl rm
syscallbypid-nd.8	1089	0644	edit dl rm
syscallbypid-nd.meta	404	0644	edit dl rm
syscallbypid-nd.stp	1100	0755	edit dl rm
syscallbypid-nd_example.txt	9322	0644	edit dl rm

Edit: /usr/share/systemtap/examples/lwtools/fsslower-nd_example.txt (1938B)

Examples of fsslower-nd.stp, the Linux SystemTap version.

This tool prints event-by-event details for each file system synchronous read
or write slower than a threshold. It works by dynamically traces two common
file system functions: do_sync_read() and do_sync_write(). Many, but not all,
file systems and workloads use these functions. Tracing their time provides one
view of suffered file system latency.

Tracing FS sync reads and writes slower than 5 ms:

# ./fsslower-nd.stp 5
Tracing FS sync reads and writes slower than 5 ms... Hit Ctrl-C to end.
TIME     PID    COMM             FUNC           SIZE     LAT(ms)
22:27:28 2346   randread.pl      do_sync_read   8192          11
22:27:28 2346   randread.pl      do_sync_read   8192          14
22:27:28 2346   randread.pl      do_sync_read   8192           6
22:27:28 2346   randread.pl      do_sync_read   8192           5
22:27:28 2346   randread.pl      do_sync_read   8192           6
22:27:28 2346   randread.pl      do_sync_read   8192           5
22:27:28 2346   randread.pl      do_sync_read   8192          24
22:27:28 2346   randread.pl      do_sync_read   8192          12
22:27:28 2346   randread.pl      do_sync_read   8192           9
22:27:28 2346   randread.pl      do_sync_read   8192           9
22:27:28 2346   randread.pl      do_sync_read   8192           5
22:27:28 2346   randread.pl      do_sync_read   8192           8
22:27:28 2346   randread.pl      do_sync_read   8192          14
22:27:28 2346   randread.pl      do_sync_read   8192          10
22:27:28 2346   randread.pl      do_sync_read   8192           6
22:27:28 2346   randread.pl      do_sync_read   8192           5
[...]

This shows that the randread.pl process was suffering latency up to 26 ms, when
issuing do_sync_read()s of 8 Kbytes.

As this is designed to be a non-debuginfo tool, there are not that many details
available. Investigate further using other tools and custom SystemTap.

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