On Apr 16, 2009, at 8:33 PM, Kevin Constantine wrote:
Trond Myklebust wrote:
On Wed, 2009-04-15 at 13:30 -0700, Kevin Constantine wrote:
Has there been any effort to expose caching statistics to the end
user? On the client-side, it would be useful to see how much
data is being re-used from cache vs data that gets retrieved over
the wire. Similarly on the server side, it would be nice to see
how much data is being served from cache vs having to pull the
data from disk.
Just wondering if anyone started anything to expose this sort of
information.
See the nfs-iostat tool in the nfs-utils package:
http://git.linux-nfs.org/?p=steved/nfs-utils.git;a=tree;f=tools/nfs-iostat;h=929e303cc762a68dfd01546f5150eb294274164e;hb=refs/heads/master
Note that you need a 2.6.17 kernel or newer.
Cheers
Trond
Thanks Trond-
It seems like nfs-iostat is displaying the number of pages that are
being written to the read/write caches (i'm only looking at the
client-side at the moment), and what I'm interested in is the ratio
of pages being read from cache vs data being fetched from the server.
Is there any documentation on the layout of /proc/self/mountstats?
Take a look at the python code in nfs-iostat or mountstats. Besides
documenting the layout of /proc/self/mountstats, there may also be
some code in there that shows how to compute cache hit ratios.
The __print_data_cache_stats function in nfs-iostat does just this for
the page cache, but I don't see it called anywhere.
Note these scripts are not finished, which is why they are currently
not installed by default.
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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