Re: 2.5.38-mm3

On Fri, Sep 27, 2002 at 08:04:31AM -0700, Martin J. Bligh wrote:

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What application were you all running ?

Kernel compile on NUMA-Q looks like this:

125673 total
82183 default_idle
2288 d_lookup
1921 vm_enough_memory
1883 __generic_copy_from_user
1566 file_read_actor
1381 .text.lock.file_table           <-------------

More likely, this is contention for the files_lock. Do you have any 
lockmeter data ?  That should give us more information. If so,
the files_struct_rcu isn't likely to help.

1168 find_get_page
1116 get_empty_filp

Presumably that's the same thing? Interestingly, if I look back at 
previous results, I see it's about twice the cost in -mm as it is 
in mainline, not sure why ... at least against 2.5.37 virgin it was.

Not sure why it shows up more in -mm, but likely because -mm has
lot less contention on other locks like dcache_lock.

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Please try running the files_struct_rcu patch where fget() is lockfree
and let me know what you see.

Will do ... if you tell me where it is ;-)

Oh, the usual place -
http://sourceforge.net/project/showfiles.php?group_id=8875&release_id=112473
I wish sourceforge FRS continued to allow direct links to patches.

Thanks
-- 
Dipankar Sarma  [off-list ref] http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.
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