Re: should ia64_spinlock_contention do backoff?

From: John Hawkes <hawkes_at_sgi.com>
Date: 2004-03-28 12:37:39
> >>>>> Chris Wedgwood wrote on Fri, March 26, 2004 3:41 PM
> > Does anyone have any idea what locks are most heavily contented for
> > ia64 right now?
>
> This question is a bit too broad, lock contention highly depends on
workload.

I totally agree.

On one AIM7-like workload that I'm using, at 64p the dominant contention is
doing pte_chain_lock() in page_remove_rmap() (11% of the cycles) and
page_add_rmap() (5%).  That's not spinlock contention -- it's cacheline
contention.  That same workload at 96p shows about 47% of the kernel cycles in
find_get_page() doing the spin_lock(mapping->page_lock), and the
pte_chain_lock() bottleneck has faded into insignificance.

John Hawkes

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Received on Sat Mar 27 21:39:35 2004

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