Date: Mon, 13 May 2013 20:59:52 +0200 From: Attilio Rao <attilio@freebsd.org> To: John Baldwin <jhb@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: <CAJ-FndAkZrt1qAQHOR6-bO1JN5KoTsQ7T4MDkcjkQge7dcs0dw@mail.gmail.com> In-Reply-To: <519134BB.5030400@FreeBSD.org> References: <201305120153.r4C1r3DN071206@svn.freebsd.org> <51912816.1020603@FreeBSD.org> <CAJ-FndDVrN8STQOmiYM91eyyY5FG1V8OP3wNKdjyuR5yemWaSQ@mail.gmail.com> <519134BB.5030400@FreeBSD.org>
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On Mon, May 13, 2013 at 8:45 PM, John Baldwin <jhb@freebsd.org> wrote: > 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. I wrote the code so I certainly read it. > 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. It is not true. vm_phys_alloc_domain_pages() (if this is what you are speaking about) doesn't have internally i < vm_ndomains. > 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. I don't mind either way. This means I should do a version that accepts domain for vm_phys_alloc_freelist_pages(). I just thought this version is smaller. Attilio -- Peace can only be achieved by understanding - A. Einstein
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