From mboxrd@z Thu Jan 1 00:00:00 1970 From: "John Hawkes" Date: Sun, 28 Mar 2004 02:37:39 +0000 Subject: Re: should ia64_spinlock_contention do backoff? Message-Id: <00c101c4146d$bf3f1630$6400a8c0@PCJohn> List-Id: References: <200403251941.i2PJfrTH026392@napali.hpl.hp.com> In-Reply-To: <200403251941.i2PJfrTH026392@napali.hpl.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org > >>>>> 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