Skip to content

Doc: explain why the offsets in MPI-IO module may not be the true values #1103

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 12, 2025
Merged

Doc: explain why the offsets in MPI-IO module may not be the true values #1103

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 7 additions & 1 deletion darshan-util/doc/darshan-util.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1426,7 +1426,13 @@ understanding how MPI-IO read or write operations map to underlying POSIX read
or write operations issued to the traced file.

The output format for the DXT MPI-IO module is essentially identical to the DXT
POSIX module, except that the offset of file operations is not tracked.
POSIX module, except that the offsets of file operations may not reflect the
true file offsets used in individual I/O operations, due to the possibility of
a very complicate MPI fileview passed to the MPI-IO library from the
application or high-level I/O libraries. Decoding a complicate MPI derived
datatype can be expensive. In addition, for MPI-IO functions that make use of
shared file pointers, e.g. ``MPI_File_write_shared()``, it is difficult to
trace the offsets without inter-process communication.

Other darshan-util utilities
=======================================
Expand Down
Loading