Re: is_head_of_free_region slowing down swsusp

[Pavel Machek <pavel@ucw.cz>]

Hi!

> is_head_of_free_region with count_and_copy_zone results results in
> pretty nasty O(number_of_free_regions^2) behaviour, and some users see
> cpu spending 40 seconds there :-(.
> 
> Actually count_and_copy_zone would probably be happy with
> "is_free_page()".
> 
> I asked Lukas (who is seeing this problem) to kill locking from
> is_head_of_free_region [we are running singlethreaded at this point,
> so it should be ok]. Do you have any other ideas?

Thanks to Lukas Horalek for some timing info....

I now reproduced in on my machine. updatedb is enough to trigger
40seconds of copying. Killing locking does not help :-(.

								Pavel
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