Chuck Lever wrote:
On Apr 21, 2009, at 1:57 PM, Kevin Constantine wrote:
Chuck Lever wrote:
On Apr 20, 2009, at 10:03 PM, Kevin Constantine wrote:
Print statistics about bytes written by NFS
Signed-off-by: Kevin Constantine
<kevin.constantine@xxxxxxxxxxxxxxxxxxx>
---
tools/nfs-iostat/nfs-iostat.py | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/tools/nfs-iostat/nfs-iostat.py
b/tools/nfs-iostat/nfs-iostat.py
index d331a72..5f2e232 100644
--- a/tools/nfs-iostat/nfs-iostat.py
+++ b/tools/nfs-iostat/nfs-iostat.py
@@ -221,6 +221,7 @@ class DeviceData:
"""
nfs_stats = self.__nfs_data
app_bytes_read = float(nfs_stats['normalreadbytes'] +
nfs_stats['directreadbytes'])
+ bytes_written_by_app = float(nfs_stats['normalwritebytes']
+ nfs_stats['directwritebytes'])
if app_bytes_read != 0:
read_bytes_from_server = float(nfs_stats['serverreadbytes'])
directio_bytes_from_server =
float(nfs_stats['directreadbytes'])
@@ -234,6 +235,15 @@ class DeviceData:
cached_read_bytes / 1024.0 / 1024.0, \
app_bytes_read / 1024.0 / 1024.0, \
ratio)
+ if bytes_written_by_app != 0:
+ bytes_written_by_nfs = float(nfs_stats['serverwritebytes'])
+ cached_write_bytes = float(bytes_written_by_app -
bytes_written_by_nfs);
Again, I don't see why this computation is necessary: The
"normalwritebytes" statistic is what was written through the client's
cache, and "directwritebytes" counts the number of bytes that were
written via O_DIRECT.
As I said in the email preceding these patches:
"I'm not quire sure about this patch. I'm seeing oddities where the
number of bytes in "NORMALWRITTENBYTES + DIRECTWRITTENBYTES" does not
equal SERVERWRITTENBYTES. In some cases the amount of data written by
the app (normalwrittenbytes + directwrittenbytes) is greater than the
amount of data written to the server, and in other cases it's less
than the amount of data written to the server. At the moment, i've
ascribed that difference to data being written to the local cache and
not flushed, but that doesn't make a whole lot of sense."
Our e-mail system may have barfed on my earlier reply, but I would like
to understand why you need this statistic. What kind of analysis are
you looking for on the write side?
As far as writes go, all I really wanted to print is MB being written to
the nfs server. But I noticed along the way that the values don't add
up and found it odd.
An application writing data to an nfs server should be getting counted
by either normalwrittenbytes, or directwrittenbytes. The data being
written by the nfs by an NFS write request should be counted by
serverwrittenbytes. normal + direct should equal server, but it
doesn't, and I'm wondering what happened to those bytes. Sometimes
normal + direct > server, sometimes normal + direct < server.
What I have in the patch doesn't really matter because I don't
understand the imbalance in the counters.
-kevin
+ print
+ print '%13s %12s %15s %15s' % ("Data Written:", "To
Server", "To Cache", "Total")
+ print '%10s %13.4fMB %13.4fMB %13.4fMB' % ("", \
+ bytes_written_by_nfs / 1024.0 / 1024.0, \
+ cached_write_bytes / 1024.0 / 1024.0, \
+ bytes_written_by_app / 1024.0 / 1024.0)
def __print_attr_cache_stats(self, sample_time):
"""Print attribute cache efficiency stats
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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