On Apr 21, 2009, at 4:39 PM, Kevin Constantine wrote:
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.
If you want to see how much data is going from the client to the
server, use serverwrittenbytes. No user-space computation is required.
The other two measure data coming in from system calls. The VFS and
the NFS client do some write caching. The instantaneous sum of these
two will not always be the same as what is written on the wire.
-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
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
--
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