Re: 2.5.38-mm3

Dipankar Sarma
2002-09-27T17:14:24Z

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

>
> > 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 <dipankar@in.ibm.com> http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.