Re: Where is the performance bottleneck?

[Nick Piggin <nickpiggin@yahoo.com.au>]

Holger Kiehl wrote:

> 3236497 total                                      1.4547
> 2507913 default_idle                             52248.1875
> 158752 shrink_zone                               43.3275
> 121584 copy_user_generic_c                      3199.5789
>  34271 __wake_up_bit                            713.9792
>  31131 __make_request                            23.1629
>  22096 scsi_request_fn                           18.4133
>  21915 rotate_reclaimable_page                   80.5699
           ^^^^^^^^^

I don't think this function should be here. This indicates that
lots of writeout is happening due to pages falling off the end
of the LRU.

There was a bug recently causing memory estimates to be wrong
on Opterons that could cause this I think.

Can you send in 2 dumps of /proc/vmstat taken 10 seconds apart
while you're writing at full speed (with 2.6.13 or the latest
-git tree).

A dump of /proc/zoneinfo and /proc/meminfo while the write is
going on would be helpful too.

Thanks,
Nick

--
SUSE Labs, Novell Inc.

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