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Date:      Mon, 4 Feb 2002 17:28:33 +0500
From:      Sergey Gershtein <sg@ur.ru>
To:        Peter Jeremy <peter.jeremy@alcatel.com.au>
Cc:        freebsd-stable@FreeBSD.ORG
Subject:   FS gurus needed! (was: Strange lock-ups during backup over nfs after adding 1024M RAM)
Message-ID:  <114283707399.20020204172833@ur.ru>
In-Reply-To: <20020204130730.B72285@gsmx07.alcatel.com.au>
References:  <20020126204941.H17540-100000@resnet.uoregon.edu> <1931130530386.20020128130947@ur.ru> <20020130073449.B78919@gsmx07.alcatel.com.au> <791310002584.20020130150111@ur.ru> <20020131111153.Y72285@gsmx07.alcatel.com.au> <1427021336.20020201123650@ur.ru> <20020204130730.B72285@gsmx07.alcatel.com.au>

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On Monday, February 04, 2002 Peter Jeremy <peter.jeremy@alcatel.com.au> wrote:

PJ> On 2002-Feb-01 12:36:50 +0500, Sergey Gershtein <sg@ur.ru> wrote:
>>Here's what "vmstat -m" says about "FFS node":
>>
>>Memory statistics by type                          Type  Kern
>>        Type  InUse MemUse HighUse  Limit Requests Limit Limit Size(s)
>>     ...
>>     FFS node152293 76147K  76479K102400K  3126467    0     0  512
>>     ...

PJ> One oddity here is the Size - "FFS node" is used to allocate struct
PJ> inode's and they should be 256 bytes on i386.  Are you using something
PJ> other than an i386 architecture?  Unless this is a cut-and-paste
PJ> error, I suspect something is radically wrong with your kernel.

Yes, it's i386 and it's not cut-and-paste error.

The current output of vmstat -m says:

     ...
     FFS node152725 76363K  76479K102400K  9247602    0     0  512
     ...
     vfscache157865 10671K  11539K102400K  9668497    0     0  64,128,256,512,512K
     ...
     
The system uptime is 5 days, backup is temporarily disabled.

I put the coplete output of 'vmstat -m', some other commands and
kernel config on the web on http://storm.mplik.ru/fbsd-stable/ so you
can have a look at it.

By the way, on our second server running the same hardware the size of
"FFS node" is also 512. How can it be so?

PJ> By default, the memory limit is 1/2 vm_kmem_size, which is 1/3 physical
PJ> memory, capped to 200MB.  Which means you've hit the default cap.

PJ> You can increase this limit with the loader environment
PJ> kern.vm.kmem.size (see loader(8) for details).  (This is also capped
PJ> at twice the physical memory - which won't affect you).  Before you go
PJ> overboard increasing this, note that the kernel virtual address space
PJ> is only 1GB.

Hmm.  Not sure what to do.  Shell I try to play with kern.vm.kmem.size
or better not touch it?  I am now thinking that removing the extra
memory we've added is the best solution to the problem. I don't like
this solution though.

PJ> How many open files do you expect on your box?
PJ> Is it reasonable for there to be >>150,000 active inodes?

ptat -T right now says:

666/4096 files
0M/511M swap space

I don't expect the number of open files go beyond 1,000-1,500.  The
only problem is accessing a lot (more than a 1,000,000) of small files
over NFS.  But if I understand correctly, those files should be opened
and closed one by one, not all together. Is that right?

PJ> Does "vfscache" have around the same number of InUse entries as "FFS node"?

Yes, it seems so (see above).  What does it mean?

PJ> What is the output of "sysctl vfs"?

See http://storm.mplik.ru/fbsd-stable/sysctl_vfs.txt

PJ> PS: I'm still hoping that one of the FS gurus will step in and point
PJ>     out what's wrong.

I changed the subject of my message to catch attention of FS gurus on
the list.

Thank you,
Sergey


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