Re: [PATCH] NFS: include filelayout DS rpc stats in mountstats

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Feb 9, 2012, at 2:58 PM, Myklebust, Trond wrote:

> On Thu, 2012-02-09 at 19:48 +0000, Adamson, Dros wrote:
>>> 
>>>> I do have an implementation that doesn't need to walk the deviceid list by allowing a shared rpc_iostats struct between multiple rpc_clients (in addition to the current rpc_iostats structure), but that required adding locking and reference counting -- all for printing stats (obviously not what we want).
>>> 
>>> This might be more in line with what we want. Note that it should be
>>> easy to clone an rpc_client and then replace its rpc_iostats struct. I
>>> don't think that needs any extra locking. We're already ignoring locking
>>> here between different rpc_tasks, so throwing in different rpc_clients
>>> to the mix will make no difference.
>> 
>> Yeah, that's easy enough and i guess we could ignore locking, but we are still left with the same problem: how is this supposed to account for different mount points using the same nfs_client?  nfs_client only has one rpc_client member.  I doubt we want to make a hash lookup on nfs_server to get the right rpc_client (which could all use the same underlying xprt).
>> 
>> Maybe it's time to move these stats into fs/nfs/ where they really belong?  We could get rid of the hack that overloads procnum with opnum from inside the compound for v4+ and finally only show a specific mount's RPC stats.
> 
> Actually, how about just adding a callback into struct rpc_call_ops
> that, if it is defined, would be called instead of rpc_count_iostats(). 
> If you then modify rpc_count_iostats() to take the 'stats' variable as a
> parameter, you can simply have the new callback call rpc_count_iostats
> with the right arguments.

Yeah, that could work!  On my walk home from the cafe (they always seem to help) I came up with a slightly different strategy:

- remove the cl_metrics (struct rpc_iostats) member from rpc_clnt
- add an *optional* rpc_iostats pointer to rpc_task (ignored if NULL)
- allocate one rpc_iostats structure (really array of structs, but you know what I mean) per nfs_server structure
- when setting up rpc_tasks in nfs-land, pass the correct rpc_iostats

with this strategy we don't accumulate stats when they aren't ever used (like an rpc_client used for mount protocol).  again, only NFS uses the rpc stats interface.

I kind of like this better than a callback, but either way is fine with me.  Which way would you prefer?

-dros

> 
> -- 
> Trond Myklebust
> Linux NFS client maintainer
> 
> NetApp
> Trond.Myklebust@xxxxxxxxxx
> www.netapp.com
> 

Attachment: smime.p7s
Description: S/MIME cryptographic signature


[Index of Archives]     [Linux Filesystem Development]     [Linux USB Development]     [Linux Media Development]     [Video for Linux]     [Linux NILFS]     [Linux Audio Users]     [Yosemite Info]     [Linux SCSI]

  Powered by Linux