Date: Mon, 13 May 2013 14:45:15 -0400 From: John Baldwin <jhb@FreeBSD.org> To: attilio@FreeBSD.org Cc: src-committers@freebsd.org, svn-src-user@freebsd.org Subject: Re: svn commit: r250543 - user/attilio/jeff-numa/sys/vm Message-ID: <519134BB.5030400@FreeBSD.org> In-Reply-To: <CAJ-FndDVrN8STQOmiYM91eyyY5FG1V8OP3wNKdjyuR5yemWaSQ@mail.gmail.com> References: <201305120153.r4C1r3DN071206@svn.freebsd.org> <51912816.1020603@FreeBSD.org> <CAJ-FndDVrN8STQOmiYM91eyyY5FG1V8OP3wNKdjyuR5yemWaSQ@mail.gmail.com>
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On 5/13/13 2:23 PM, Attilio Rao wrote: > On Mon, May 13, 2013 at 7:51 PM, John Baldwin <jhb@freebsd.org> wrote: >> On 5/11/13 9:53 PM, Attilio Rao wrote: >>> Author: attilio >>> Date: Sun May 12 01:53:03 2013 >>> New Revision: 250543 >>> URL: http://svnweb.freebsd.org/changeset/base/250543 >>> >>> Log: >>> Scan all the domains when trying to allocate from freepages. >>> Some domains may be empty but others may still have some available pages >>> satisfying the allocations. >> >> It seems like you have nested loops here so you are doing N^2 scans >> rather than N? > > If you want to say so. In most cases N=2 and M=4. However also > consider the less overhead caming from all the adjustement of the > flind because of now split DOMAINS-NFREELISTS concepts. *sigh* No. Read the code. vm_phys_alloc_pages() does 'for i = 0; i < vm_ndomains; i++' around calls to vm_phys_alloc_pages_domain() which internally has its _own_ 'for i = 0; i < vm_ndomains; i++'. Same with vm_phys_alloc_freelist_pages(). You don't need it in both places. Also, vm_phys_alloc_pages() should now be able to just call vm_phys_alloc_freelist_pages() and just be a simple loop that only iterates on flind as it used to do before all the NUMA changes. -- John Baldwin
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