From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <468439E8.4040606@redhat.com> Date: Thu, 28 Jun 2007 18:44:56 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 01 of 16] remove nr_scan_inactive/active References: <8e38f7656968417dfee0.1181332979@v2.random> <466C36AE.3000101@redhat.com> <20070610181700.GC7443@v2.random> <46814829.8090808@redhat.com> <20070626105541.cd82c940.akpm@linux-foundation.org> In-Reply-To: <20070626105541.cd82c940.akpm@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Andrea Arcangeli , linux-mm@kvack.org List-ID: Andrew Morton wrote: > Where's the system time being spent? OK, it turns out that there is quite a bit of variability in where the system spends its time. I did a number of reaim runs and averaged the time the system spent in the top functions. This is with the Fedora rawhide kernel config, which has quite a few debugging options enabled. _raw_spin_lock 32.0% page_check_address 12.7% __delay 10.8% mwait_idle 10.4% anon_vma_unlink 5.7% __anon_vma_link 5.3% lockdep_reset_lock 3.5% __kmalloc_node_track_caller 2.8% security_port_sid 1.8% kfree 1.6% anon_vma_link 1.2% page_referenced_one 1.1% In short, the system is waiting on the anon_vma lock. I wonder if Lee Schemmerhorn's patch to turn that spinlock into an rwlock would help this workload, or if we simply should scan fewer pages in the pageout code. Andrea, with your VM patches for some reason the number of users where reaim has its crossover point is also somewhat variable, between 4200 and 5100 users, with 9 out of 10 runs under 4500 on my system. A kernel without your patches is not as variable, but has visibly more unfairness between tasks, as seen in the reaim "Std_dev" columns. -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org