Re: mmap over nfs leads to excessive system load

[Chuck Lever <cel@citi.umich.edu>]

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Trond Myklebust wrote:
> On Wed, 2005-11-16 at 14:39 -0800, Kenny Simpson wrote:
> 
>>--- Trond Myklebust <trond.myklebust@fys.uio.no> wrote:
>>
>>>I'm getting lost here. Please could you spell out the testcases that are
>>>not working.
>>
>>I've redone my test cases and have confirmed that O_DIRECT with pwrite64 triggers the bad
>>condition.
>>
>>The cases that are fine are:
>>  pwrite64
>>  ftruncate with O_DIRECT
>>  ftruncate
>>
>>Also, when the system is in this state, if I try to 'ls' the file,
>>the 'ls' process becomes stuck in state D in sync_page.  stracing the 'ls'
>>shows it is in a call to stat64.
>>
>>-Kenny
> 
> 
> Chuck, can you take a look at this?
> 
> Kenny is seeing a hang when using pwrite64() on an O_DIRECT file
> and the file size exceeds 4Gb. Server is a NetApp filer w/ NFSv3.
> 
> I had a quick look at nfs_file_direct_write(), and among other things,
> it would appear that it is not doing any of the usual overflow checks on
> *pos and the count size (see generic_write_checks()). In particular,
> checks are missing against overflow vs. MAX_NON_LFS if O_LARGEFILE is
> not set (and also against overflow vs. s_maxbytes, but that is less
> relevant here).

'uname -a' on the client?


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