Re: heavy VM load due to revamped pagebuf locking?

[Stephen Lord <lord@xxxxxxx>]

Andi Kleen wrote:

> On Thu, Apr 04, 2002 at 11:13:39AM -0500, HABBINGA,ERIK (HP-Loveland,ex1) wrote:
>
> > I've updated to 2.4.18 w/ a XFS CVS download from 03/29/2002.  During SPEC
> > testing, the VM takes over all CPU load as pagebuf_iostart starts waiting
> > for memory, and then kmalloc starts waiting for memory.  All of this time
> > spent in shrink_cache causes the SPEC test to time out.  Once the test
> > stops, the box settles down and VM CPU load goes away.    All of the
> > shrink_cache functions are waiting for schedule() to come back, because of
> > the test for current->need_resched at the top of the shrink_cache loop.  For
> > grins, I commented out that test, and now many nfsd processes are sitting in
> > _pagebuf_find_lockable_buffer->pagebuf_iostart's call to pagebuf_iowait.
> > Could the revamped pagebuf locking cause this behaviour?
>
> You could test ist. Just revert that TAKE and test again.
>
> -Andi
Andi's suggestion is a good one, we have not seen this here, your 
configuation is
clearly larger than anything we have locally.

You might also try just reverting the changes in page_buf_io.c (you will 
need
the header file change). The locking changes should not affect memory
consumption that much, but changes went into this file which put buffer
heads on pages in more circumstances than we used to.

Steve