diff options
| author | Mateusz Piotrowski <0mp@FreeBSD.org> | 2025-10-26 16:52:11 +0000 |
|---|---|---|
| committer | Mateusz Piotrowski <0mp@FreeBSD.org> | 2025-10-31 15:52:20 +0000 |
| commit | db25448ab9ffa8bfe52d852674cc466494b849d1 (patch) | |
| tree | d983893382c0890991a7e46666de0300ab3497b7 | |
| parent | bd27bd1f51d049538cc7a0053be9d99110a53ae1 (diff) | |
dtrace_io.4: Use bio_length instead of bio_bcount in examples
Tracing bio_bcount makes little sense for some devices like for example
md(4), as it is set to "0" instead of to the actual I/O length.
markj@ suggested the following DTrace one-liner to identify some cases
where bio_length is set but bio_bcount is not:
dtrace -n 'io:::start /args[0]->bio_length != args[0]->bio_bcount/{printf("%d %d", args[0]->bio_length, args[0]->bio_bcount); stack();}'
For future reference in the context of bio_length vs bio_bcount,
phk@ mentioned in the code review that:
> the original intent was to get rid of of bio_bcount
Reviewed by: markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D53365
| -rw-r--r-- | share/man/man4/dtrace_io.4 | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/share/man/man4/dtrace_io.4 b/share/man/man4/dtrace_io.4 index 30ec44768fbf..1699cebab8e9 100644 --- a/share/man/man4/dtrace_io.4 +++ b/share/man/man4/dtrace_io.4 @@ -22,7 +22,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd April 18, 2015 +.Dd October 26, 2025 .Dt DTRACE_IO 4 .Os .Sh NAME @@ -84,7 +84,7 @@ The following script shows a per-process breakdown of total I/O by disk device: io:::start { - @[args[1]->device_name, execname, pid] = sum(args[0]->bio_bcount); + @[args[1]->device_name, execname, pid] = sum(args[0]->bio_length); } END |