Slow NFS loop performance.

Slow NFS loop performance.

[dE .]

Humm... The last thing I expected was no response even in the mailing list.

So I'm filing a bug on this.

On Oct 23, 2012 2:19 PM, "dE ." <de.techno@gmail.com> wrote:
 > Hi!
 >
 > Great job with NFS server, it surely is fast, but not on loop devices.
 >
 > If I loop mount a file and share the mount point over NFS3 or NFS4, the
 > write performance of the client on the loop mounted share is pretty bad.
 >
 > On a 100 Mbps (or 12.5MBps) full duplex Ethernet link, I get ~8MBps
 > speeds, whereas on the loop mounted device, I get at best 6MBps.
 >
 > Any ideas why?
 >
 > My server configuration (NFS4) --
 > anonuid=1000,anongid=1000,**secure,no_subtree_check,rw,**fsid=0,crossmnt
 >
 > My client mount options --
 > rsize=1048576,wsize=1048576,**async,hard,timeo=60,retrans=2,**
 > actimeo=900,retry=2,**lookupcache=pos,nfsvers=4,**
 > nolock,intr,noacl,rdirplus
 >

Re: Slow NFS loop performance.

[J. Bruce Fields]

On Fri, Nov 23, 2012 at 04:31:55PM +0530, dE . wrote:
> Humm... The last thing I expected was no response even in the mailing list.
> 
> So I'm filing a bug on this.
> 
> On Oct 23, 2012 2:19 PM, "dE ." <de.techno@gmail.com> wrote:
> > Hi!
> >
> > Great job with NFS server, it surely is fast, but not on loop devices.
> >
> > If I loop mount a file and share the mount point over NFS3 or NFS4, the
> > write performance of the client on the loop mounted share is pretty bad.
> >
> > On a 100 Mbps (or 12.5MBps) full duplex Ethernet link, I get ~8MBps
> > speeds, whereas on the loop mounted device, I get at best 6MBps.

What exactly is your test?

--b.

> >
> > Any ideas why?
> >
> > My server configuration (NFS4) --
> > anonuid=1000,anongid=1000,**secure,no_subtree_check,rw,**fsid=0,crossmnt
> >
> > My client mount options --
> > rsize=1048576,wsize=1048576,**async,hard,timeo=60,retrans=2,**
> > actimeo=900,retry=2,**lookupcache=pos,nfsvers=4,**
> > nolock,intr,noacl,rdirplus
> >
> 
> --
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html

RE: Slow NFS loop performance.

[Myklebust, Trond]

You're using a non-default timeo=60 on a TCP connection.

Why?

> -----Original Message-----
> From: linux-nfs-owner@vger.kernel.org [mailto:linux-nfs-
> owner@vger.kernel.org] On Behalf Of dE .
> Sent: Friday, November 23, 2012 6:02 AM
> To: linux-nfs@vger.kernel.org
> Subject: Slow NFS loop performance.
> 
> Humm... The last thing I expected was no response even in the mailing list.
> 
> So I'm filing a bug on this.
> 
> On Oct 23, 2012 2:19 PM, "dE ." <de.techno@gmail.com> wrote:
>  > Hi!
>  >
>  > Great job with NFS server, it surely is fast, but not on loop devices.
>  >
>  > If I loop mount a file and share the mount point over NFS3 or NFS4, the  >
> write performance of the client on the loop mounted share is pretty bad.
>  >
>  > On a 100 Mbps (or 12.5MBps) full duplex Ethernet link, I get ~8MBps  >
> speeds, whereas on the loop mounted device, I get at best 6MBps.
>  >
>  > Any ideas why?
>  >
>  > My server configuration (NFS4) --
>  >
> anonuid=1000,anongid=1000,**secure,no_subtree_check,rw,**fsid=0,cross
> mnt
>  >
>  > My client mount options --
>  > rsize=1048576,wsize=1048576,**async,hard,timeo=60,retrans=2,**
>  > actimeo=900,retry=2,**lookupcache=pos,nfsvers=4,**
>  > nolock,intr,noacl,rdirplus
>  >
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the
> body of a message to majordomo@vger.kernel.org More majordomo info at
> http://vger.kernel.org/majordomo-info.html

Re: Slow NFS loop performance.

[dE .]

On 11/23/12 22:53, J. Bruce Fields wrote:
> On Fri, Nov 23, 2012 at 04:31:55PM +0530, dE . wrote:
>> Humm... The last thing I expected was no response even in the mailing list.
>>
>> So I'm filing a bug on this.
>>
>> On Oct 23, 2012 2:19 PM, "dE ."<de.techno@gmail.com>  wrote:
>>> Hi!
>>>
>>> Great job with NFS server, it surely is fast, but not on loop devices.
>>>
>>> If I loop mount a file and share the mount point over NFS3 or NFS4, the
>>> write performance of the client on the loop mounted share is pretty bad.
>>>
>>> On a 100 Mbps (or 12.5MBps) full duplex Ethernet link, I get ~8MBps
>>> speeds, whereas on the loop mounted device, I get at best 6MBps.
> What exactly is your test?
>
> --b.

Sorry for the late response. I'd 200+ unread mails.

I'm writing a large file to the mounted loop device.

Re: Slow NFS loop performance.

[dE .]

On 11/24/12 00:34, Myklebust, Trond wrote:
> You're using a non-default timeo=60 on a TCP connection.
>
> Why?

This's a LAN with just 2 PCs. So there're no packet drops, so there's no 
point resending requests frequently.

Re: Slow NFS loop performance.

[J. Bruce Fields]

On Mon, Nov 26, 2012 at 09:28:06PM +0530, dE . wrote:
> On 11/23/12 22:53, J. Bruce Fields wrote:
> >On Fri, Nov 23, 2012 at 04:31:55PM +0530, dE . wrote:
> >>Humm... The last thing I expected was no response even in the mailing list.
> >>
> >>So I'm filing a bug on this.
> >>
> >>On Oct 23, 2012 2:19 PM, "dE ."<de.techno@gmail.com>  wrote:
> >>>Hi!
> >>>
> >>>Great job with NFS server, it surely is fast, but not on loop devices.
> >>>
> >>>If I loop mount a file and share the mount point over NFS3 or NFS4, the
> >>>write performance of the client on the loop mounted share is pretty bad.
> >>>
> >>>On a 100 Mbps (or 12.5MBps) full duplex Ethernet link, I get ~8MBps
> >>>speeds, whereas on the loop mounted device, I get at best 6MBps.
> >What exactly is your test?
> >
> >--b.
> 
> Sorry for the late response. I'd 200+ unread mails.
> 
> I'm writing a large file to the mounted loop device.

How large, and do you have the exact command you're using for that?

Also, what are the client and server versions?

I don't have any good idea off the top of my head.  I doubt anyone's
worked on optimizing exports of loop devices.  I guess the first step
would be to collect some statistics in the two cases (loop device and
non-loop device), compare them, and see if you can see any patterns.
/proc/self/mountstats on the client, and /proc/fs/nfsd/pool_stats, on
the server, would be starting points.  Maybe perf on the server could
also show up something.  Just running "top" on the server might be
interesting.  (E.g.  is the CPU obviously busier in the slow case?)

--b.

Re: Slow NFS loop performance.

[dE .]

On 11/26/12 21:38, J. Bruce Fields wrote:
> On Mon, Nov 26, 2012 at 09:28:06PM +0530, dE . wrote:
>> On 11/23/12 22:53, J. Bruce Fields wrote:
>>> On Fri, Nov 23, 2012 at 04:31:55PM +0530, dE . wrote:
>>>> Humm... The last thing I expected was no response even in the mailing list.
>>>>
>>>> So I'm filing a bug on this.
>>>>
>>>> On Oct 23, 2012 2:19 PM, "dE ."<de.techno@gmail.com>   wrote:
>>>>> Hi!
>>>>>
>>>>> Great job with NFS server, it surely is fast, but not on loop devices.
>>>>>
>>>>> If I loop mount a file and share the mount point over NFS3 or NFS4, the
>>>>> write performance of the client on the loop mounted share is pretty bad.
>>>>>
>>>>> On a 100 Mbps (or 12.5MBps) full duplex Ethernet link, I get ~8MBps
>>>>> speeds, whereas on the loop mounted device, I get at best 6MBps.
>>> What exactly is your test?
>>>
>>> --b.
>> Sorry for the late response. I'd 200+ unread mails.
>>
>> I'm writing a large file to the mounted loop device.
> How large, and do you have the exact command you're using for that?
>
> Also, what are the client and server versions?
>
> I don't have any good idea off the top of my head.  I doubt anyone's
> worked on optimizing exports of loop devices.  I guess the first step
> would be to collect some statistics in the two cases (loop device and
> non-loop device), compare them, and see if you can see any patterns.
> /proc/self/mountstats on the client, and /proc/fs/nfsd/pool_stats, on
> the server, would be starting points.  Maybe perf on the server could
> also show up something.  Just running "top" on the server might be
> interesting.  (E.g.  is the CPU obviously busier in the slow case?)
>
> --b.

I'll try it out, but I've see no CPU usage problem here. This time I'll 
use dd (I did that previously also).

RE: Slow NFS loop performance.

[Myklebust, Trond]

> -----Original Message-----
> From: linux-nfs-owner@vger.kernel.org [mailto:linux-nfs-
> owner@vger.kernel.org] On Behalf Of dE .
> Sent: Monday, November 26, 2012 11:01 AM
> To: linux-nfs@vger.kernel.org
> Subject: Re: Slow NFS loop performance.
> 
> On 11/24/12 00:34, Myklebust, Trond wrote:
> > You're using a non-default timeo=60 on a TCP connection.
> >
> > Why?
> 
> This's a LAN with just 2 PCs. So there're no packet drops, so there's no point
> resending requests frequently.

The default is timeo=600.

Timeo=60 is a 6 second timeout, and is not only pointless for a TCP connection, it can actually cause unnecessary disruptions when you use NFSv4 because all retransmissions are required to do a TCP disconnect+reconnect cycle.

Trond

Re: Slow NFS loop performance.

[dE .]

On 11/26/12 21:38, J. Bruce Fields wrote:
> On Mon, Nov 26, 2012 at 09:28:06PM +0530, dE . wrote:
>> On 11/23/12 22:53, J. Bruce Fields wrote:
>>> On Fri, Nov 23, 2012 at 04:31:55PM +0530, dE . wrote:
>>>> Humm... The last thing I expected was no response even in the mailing list.
>>>>
>>>> So I'm filing a bug on this.
>>>>
>>>> On Oct 23, 2012 2:19 PM, "dE ."<de.techno@gmail.com>   wrote:
>>>>> Hi!
>>>>>
>>>>> Great job with NFS server, it surely is fast, but not on loop devices.
>>>>>
>>>>> If I loop mount a file and share the mount point over NFS3 or NFS4, the
>>>>> write performance of the client on the loop mounted share is pretty bad.
>>>>>
>>>>> On a 100 Mbps (or 12.5MBps) full duplex Ethernet link, I get ~8MBps
>>>>> speeds, whereas on the loop mounted device, I get at best 6MBps.
>>> What exactly is your test?
>>>
>>> --b.
>> Sorry for the late response. I'd 200+ unread mails.
>>
>> I'm writing a large file to the mounted loop device.
> How large, and do you have the exact command you're using for that?
>
> Also, what are the client and server versions?
>
> I don't have any good idea off the top of my head.  I doubt anyone's
> worked on optimizing exports of loop devices.  I guess the first step
> would be to collect some statistics in the two cases (loop device and
> non-loop device), compare them, and see if you can see any patterns.
> /proc/self/mountstats on the client, and /proc/fs/nfsd/pool_stats, on
> the server, would be starting points.  Maybe perf on the server could
> also show up something.  Just running "top" on the server might be
> interesting.  (E.g.  is the CPU obviously busier in the slow case?)
>
> --b.

It's clear --

On the loop device --

dd if=/dev/zero of=/mnt/shares/mount_point/xfs_large_files/test.zero 
bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1788.51 s, 600 kB/s

And otherwise --

dd if=/dev/zero of=/mnt/shares/test.zero bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 157.447 s, 6.8 MB/s

dd if=/dev/zero of=/mnt/shares/test.zero bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 128.628 s, 8.3 MB/s

I ran out of patience to do any tests on the loop device.

cat /proc/self/mountstats --

device rootfs mounted on / with fstype rootfs
device /dev/root mounted on / with fstype reiserfs
..
..
device 192.168.1.3:/ mounted on /mnt/shares with fstype nfs4 statvers=1.1
         opts:   
rw,vers=4.0,rsize=262144,wsize=262144,namlen=255,acregmin=900,acregmax=900,acdirmin=900,acdirmax=900,hard,proto=tcp,timeo=60,retrans=2,sec=sys,clientaddr=192.168.1.2,lookupcache=pos,local_lock=none
         age:    4026
         caps:   caps=0xffff,wtmult=512,dtsize=32768,bsize=0,namlen=255
         nfsv4:  bm0=0xfdffbfff,bm1=0xf9be3e,acl=0x3,pnfs=not configured
         sec:    flavor=1,pseudoflavor=1
         events: 14 54 0 8523 6 5 47 611072 0 0 611072 3040 12 6 12 12 0 
6 0 5 611072 0 0 0 0 0 0
         bytes:  0 2502950912 0 0 0 2502950912 0 611072
         RPC iostats version: 1.0  p/v: 100003/4 (nfs)
         xprt:   tcp 763 0 348 341795 14 30200 26072 7 42669773 0 174 
6344270 677055
         per-op statistics
                 NULL: 0 0 0 0 0 0 0 0
                 READ: 0 0 0 0 0 0 0 0
                WRITE: 10035 10035 0 2505279032 1324620 53001291 3776691 
56778324
               COMMIT: 48 48 0 10176 5952 151346 14030 165378
                 OPEN: 6 6 0 1784 2352 0 43 43
         OPEN_CONFIRM: 2 2 0 408 136 0 0 0
          OPEN_NOATTR: 0 0 0 0 0 0 0 0
         OPEN_DOWNGRADE: 0 0 0 0 0 0 0 0
                CLOSE: 6 6 0 1320 792 0 1 1
              SETATTR: 6 6 0 1432 1440 0 3478 3479
               FSINFO: 2 2 0 336 216 0 0 0
                RENEW: 0 0 0 0 0 0 0 0
          SETCLIENTID: 0 0 0 0 0 0 0 0
         SETCLIENTID_CONFIRM: 0 0 0 0 0 0 0 0
                 LOCK: 0 0 0 0 0 0 0 0
                LOCKT: 0 0 0 0 0 0 0 0
                LOCKU: 0 0 0 0 0 0 0 0
               ACCESS: 13 13 0 2568 1488 15581 8484 28896
              GETATTR: 15 15 0 2860 3300 0 7 8
               LOOKUP: 6 7 0 1472 516 19755 11318 31074
          LOOKUP_ROOT: 1 1 0 160 240 0 26 27
               REMOVE: 0 0 0 0 0 0 0 0
               RENAME: 0 0 0 0 0 0 0 0
                 LINK: 0 0 0 0 0 0 0 0
              SYMLINK: 0 0 0 0 0 0 0 0
               CREATE: 0 0 0 0 0 0 0 0
             PATHCONF: 1 1 0 164 72 0 0 0
               STATFS: 6 6 0 1128 696 0 1 1
             READLINK: 0 0 0 0 0 0 0 0
              READDIR: 3 3 0 652 3380 0 42 42
          SERVER_CAPS: 3 3 0 492 276 0 0 0
          DELEGRETURN: 0 0 0 0 0 0 0 0
               GETACL: 0 0 0 0 0 0 0 0
               SETACL: 0 0 0 0 0 0 0 0
         FS_LOCATIONS: 0 0 0 0 0 0 0 0
         RELEASE_LOCKOWNER: 0 0 0 0 0 0 0 0
              SECINFO: 0 0 0 0 0 0 0 0
          EXCHANGE_ID: 0 0 0 0 0 0 0 0
         CREATE_SESSION: 0 0 0 0 0 0 0 0
         DESTROY_SESSION: 0 0 0 0 0 0 0 0
             SEQUENCE: 0 0 0 0 0 0 0 0
         GET_LEASE_TIME: 0 0 0 0 0 0 0 0
         RECLAIM_COMPLETE: 0 0 0 0 0 0 0 0
            LAYOUTGET: 0 0 0 0 0 0 0 0
         GETDEVICEINFO: 0 0 0 0 0 0 0 0
         LAYOUTCOMMIT: 0 0 0 0 0 0 0 0
         LAYOUTRETURN: 0 0 0 0 0 0 0 0
         SECINFO_NO_NAME: 0 0 0 0 0 0 0 0
         TEST_STATEID: 0 0 0 0 0 0 0 0
         FREE_STATEID: 0 0 0 0 0 0 0 0
         GETDEVICELIST: 0 0 0 0 0 0 0 0

device 192.168.1.3:/mount_point/xfs_large_files/ mounted on 
/mnt/shares/mount_point/xfs_large_files with fstype nfs4 statvers=1.1
         opts:   
rw,vers=4.0,rsize=262144,wsize=262144,namlen=255,acregmin=900,acregmax=900,acdirmin=900,acdirmax=900,hard,proto=tcp,port=0,timeo=60,retrans=2,sec=sys,clientaddr=192.168.1.2,lookupcache=pos,local_lock=none
         age:    2344
         caps:   caps=0xffff,wtmult=512,dtsize=32768,bsize=0,namlen=255
         nfsv4:  bm0=0xfdffbfff,bm1=0xf9be3e,acl=0x3,pnfs=not configured
         sec:    flavor=1,pseudoflavor=1
         events: 0 0 0 6464 0 0 2 262144 0 0 262144 10131 0 1 2 2 0 1 0 
0 262144 0 0 0 0 0 0
         bytes:  0 1073741824 0 0 0 1073741824 0 262144
         RPC iostats version: 1.0  p/v: 100003/4 (nfs)
         xprt:   tcp 763 0 348 341795 14 30200 26072 7 42669773 0 174 
6344270 677055
         per-op statistics
                 NULL: 0 0 0 0 0 0 0 0
                 READ: 0 0 0 0 0 0 0 0
                WRITE: 7821 12504 5 1360145244 1032372 461231706 
30244294 493689738
               COMMIT: 23 28 0 5600 2852 981824 61062 1049646
                 OPEN: 1 1 0 336 404 0 122 122
         OPEN_CONFIRM: 1 1 0 216 68 0 0 0
          OPEN_NOATTR: 0 0 0 0 0 0 0 0
         OPEN_DOWNGRADE: 0 0 0 0 0 0 0 0
                CLOSE: 1 1 0 232 132 0 0 0
              SETATTR: 1 1 0 244 240 0 0 0
               FSINFO: 1 1 0 200 108 0 0 0
                RENEW: 0 0 0 0 0 0 0 0
          SETCLIENTID: 0 0 0 0 0 0 0 0
         SETCLIENTID_CONFIRM: 0 0 0 0 0 0 0 0
                 LOCK: 0 0 0 0 0 0 0 0
                LOCKT: 0 0 0 0 0 0 0 0
                LOCKU: 0 0 0 0 0 0 0 0
               ACCESS: 1 1 0 208 124 0 0 0
              GETATTR: 1 1 0 200 220 0 0 0
               LOOKUP: 0 0 0 0 0 0 0 0
          LOOKUP_ROOT: 0 0 0 0 0 0 0 0
               REMOVE: 0 0 0 0 0 0 0 0
               RENAME: 0 0 0 0 0 0 0 0
                 LINK: 0 0 0 0 0 0 0 0
              SYMLINK: 0 0 0 0 0 0 0 0
               CREATE: 0 0 0 0 0 0 0 0
             PATHCONF: 1 1 0 196 72 0 0 0
               STATFS: 0 0 0 0 0 0 0 0
             READLINK: 0 0 0 0 0 0 0 0
              READDIR: 0 0 0 0 0 0 0 0
          SERVER_CAPS: 2 2 0 392 184 0 0 0
          DELEGRETURN: 0 0 0 0 0 0 0 0
               GETACL: 0 0 0 0 0 0 0 0
               SETACL: 0 0 0 0 0 0 0 0
         FS_LOCATIONS: 0 0 0 0 0 0 0 0
         RELEASE_LOCKOWNER: 0 0 0 0 0 0 0 0
              SECINFO: 0 0 0 0 0 0 0 0
          EXCHANGE_ID: 0 0 0 0 0 0 0 0
         CREATE_SESSION: 0 0 0 0 0 0 0 0
         DESTROY_SESSION: 0 0 0 0 0 0 0 0
             SEQUENCE: 0 0 0 0 0 0 0 0
         GET_LEASE_TIME: 0 0 0 0 0 0 0 0
         RECLAIM_COMPLETE: 0 0 0 0 0 0 0 0
            LAYOUTGET: 0 0 0 0 0 0 0 0
         GETDEVICEINFO: 0 0 0 0 0 0 0 0
         LAYOUTCOMMIT: 0 0 0 0 0 0 0 0
         LAYOUTRETURN: 0 0 0 0 0 0 0 0
         SECINFO_NO_NAME: 0 0 0 0 0 0 0 0
         TEST_STATEID: 0 0 0 0 0 0 0 0
         FREE_STATEID: 0 0 0 0 0 0 0 0
         GETDEVICELIST: 0 0 0 0 0 0 0 0

And /proc/fs/nfsd/pool_stats

cat /proc/fs/nfsd/pool_stats
# pool packets-arrived sockets-enqueued threads-woken overloads-avoided 
threads-timedout
0 4637559 21028 1689208 269 0

Server --
uname -r
2.6.32-5-amd64

modinfo nfs
filename:       /lib/modules/2.6.32-5-amd64/kernel/fs/nfs/nfs.ko
license:        GPL
author:         Olaf Kirch <okir@monad.swb.de>
depends:        sunrpc,fscache,lockd,auth_rpcgss,nfs_acl
vermagic:       2.6.32-5-amd64 SMP mod_unload modversions
parm:           callback_tcpport:portnr
parm:           cache_getent:Path to the client cache upcall program 
(string)
parm:           cache_getent_timeout:Timeout (in seconds) after which 
the cache upcall is assumed to have failed (ulong)
parm:           enable_ino64:bool

modinfo nfsd
filename:       /lib/modules/2.6.32-5-amd64/kernel/fs/nfsd/nfsd.ko
license:        GPL
author:         Olaf Kirch <okir@monad.swb.de>
depends:        auth_rpcgss,sunrpc,lockd,exportfs,nfs_acl
vermagic:       2.6.32-5-amd64 SMP mod_unload modversions

Client --

uname -r
3.4.2-gentoo-r1

modinfo nfs
filename:       /lib/modules/3.4.2-gentoo-r1/kernel/fs/nfs/nfs.ko
license:        GPL
author:         Olaf Kirch <okir@monad.swb.de>
depends:        sunrpc,lockd,auth_rpcgss,nfs_acl
intree:         Y
vermagic:       3.4.2-gentoo-r1 SMP preempt mod_unload modversions
parm:           callback_tcpport:portnr
parm:           nfs_idmap_cache_timeout:int
parm:           send_implementation_id:Send implementation ID with 
NFSv4.1 exchange_id (ushort)
parm:           max_session_slots:Maximum number of outstanding NFSv4.1 
requests the client will negotiate (ushort)
parm:           cache_getent:Path to the client cache upcall program 
(string)
parm:           cache_getent_timeout:Timeout (in seconds) after which 
the cache upcall is assumed to have failed (ulong)
parm:           enable_ino64:bool
parm:           nfs4_disable_idmapping:Turn off NFSv4 idmapping when 
using 'sec=sys' (bool)

modinfo nfsd
filename:       /lib/modules/3.4.2-gentoo-r1/kernel/fs/nfsd/nfsd.ko
license:        GPL
author:         Olaf Kirch <okir@monad.swb.de>
depends:        auth_rpcgss,sunrpc,lockd,nfs_acl
intree:         Y
vermagic:       3.4.2-gentoo-r1 SMP preempt mod_unload modversions
parm:           nfs4_disable_idmapping:Turn off server's NFSv4 idmapping 
when using 'sec=sys' (bool)

net-fs/nfs-utils version 1.2.3-r1

This problem was reproducible from day 1, even during the 2.6 days. This 
also happen(ed/s) when I loop mount some file (on the server) in the client.

I also had an old Debian testing system which (Wheezy) which had 3.0 
kernel and shared the same problem.