X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=blobdiff_plain;f=lustre-iokit%2Fobdfilter-survey%2FREADME;h=fcb0b8e192e14415665943f2339fb27a37bb2a7b;hp=304672356db06144b1e6356b6e657426573a55f7;hb=00fc7ec0e84c297275f3d746b18ea0310e69cf57;hpb=d03c475e63cac8beeb20613d2e42881ae417eeb2

diff --git a/lustre-iokit/obdfilter-survey/README b/lustre-iokit/obdfilter-survey/README
index 3046723..fcb0b8e 100644
--- a/lustre-iokit/obdfilter-survey/README
+++ b/lustre-iokit/obdfilter-survey/README
@@ -12,8 +12,8 @@ This survey may be used to characterise the performance of a lustre OSS.
 It can exercise the OSS either locally or remotely via the network.
 
 The script uses lctl::test_brw to drive the echo_client doing sequential
-I/O with varying numbers of threads and objects.  One instance of lctl is
-spawned for each OST.
+I/O with varying numbers of threads and objects (files).  One instance of
+lctl is spawned for each OST.
 
 
 Running
@@ -92,7 +92,10 @@ Visualising Results
 
 I've found it most useful to import the summary data (it's fixed width)
 into Excel (or any graphing package) and graph bandwidth v. # threads for
-varying numbers of concurrent regions.  This shows how the device performs
-with varying queue depth.  If the series (varying numbers of concurrent
-regions) all seem to land on top of each other, it shows the device is
-phased by seeks at the given record size.
+varying numbers of concurrent regions.  This shows how the OSS performs for
+a given number of concurrently accessed objects (i.e. files) with varying
+numbers of I/Os in flight.  
+
+It is also extremely useful to record average disk I/O sizes during each
+test.  These numbers help find pathologies in file the file system block
+allocator and the block device elevator.