Commit 29bd2217 authored by Philip Carns's avatar Philip Carns

update runtime docs to reflect --enable-stat-at-open option


git-svn-id: https://svn.mcs.anl.gov/repos/darshan/trunk@617 3b7491f3-a168-0410-bf4b-c445ed680a29
parent a791e4a5
......@@ -40,6 +40,20 @@ make
make install
----
.Detecting file size and alignment
[NOTE]
====
You can also add --enable-stat-at-open option to cause the Darshan library
to issue an additional stat() system call on each file the first time that
it is opened on each process. This allows Darshan to detect the file
alignment (and subsequent unaligned accesses). It also allows Darshan to
detect the size of files at open time before any I/O is performed.
Unfortunately, this option can cause significant overhead at scale on file
systems such as PVFS or Lustre that must contact every server for a given
file in order to satisfy a stat request. We therefore disable this
feature by default.
====
.Explanation of configure arguments:
* `--with-mem-align` (mandatory): This value is system-dependent and will be
used by Darshan to determine if the buffer for a read or write operation is
......@@ -236,7 +250,7 @@ module swap PrgEnv-pgi PrgEnv-gnu
./configure --with-mem-align=8 \
--with-log-path=/shared-file-system/darshan-logs \
--prefix=/soft/darshan-2.2.3 \
--with-jobid-env=PBS_JOBID --disable-cuserid --enable-st-dev-workaround CC=cc
--with-jobid-env=PBS_JOBID --disable-cuserid CC=cc
make install
module swap PrgEnv-gnu PrgEnv-pgi
----
......@@ -254,11 +268,6 @@ but on some Cray environments (notably the Beagle XE6 system as of March 2012)
the cuserid() call triggers a segmentation fault. With this option set,
Darshan will typically use the LOGNAME environment variable to determine a
userid.
The --enable-st-dev-workaround argument is used to tell Darshan to
determine the device type of each file by checking the parent directory
rather than the file itself. This is a workaround for a file stat
inconsistency observed on some systems.
====
As in any Darshan installation, the darshan-mk-log-dirs.pl script can then be
......
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