Re: [PATCH] Invalidate_inodes can be very slow

[Kirill Korotaev <kk@sw.ru>]

>  > no, testcase is not available :( And it uses functionality
>  > not available in mainstream kernel. But the problem can be hit with
>  > very simple script instead:
>  >
>  > 1. mount N filesystems.
>  > 2. work on them, so that inode cache grows to its maximum
>  > possible size (it was 1,000,000 of inodes in our case).
>  > 3. umount these filesystems.
>  >
>  > During operation #3 node is very slow and it is quite noticable
>  > on ssh console when typing commands.
>
> This can be due to a number of reasons (worst case behavior of
> shrink_dcache_parent() for example). What /proc/profile shows?
I used cycles measuring patch. It showed that > 50% CPU during the test
was spent in invalidate_inodes().

Kirill