Date: Mon, 13 May 2013 15:12:44 -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: <51913B2C.9000505@FreeBSD.org> In-Reply-To: <CAJ-FndAkZrt1qAQHOR6-bO1JN5KoTsQ7T4MDkcjkQge7dcs0dw@mail.gmail.com> References: <201305120153.r4C1r3DN071206@svn.freebsd.org> <51912816.1020603@FreeBSD.org> <CAJ-FndDVrN8STQOmiYM91eyyY5FG1V8OP3wNKdjyuR5yemWaSQ@mail.gmail.com> <519134BB.5030400@FreeBSD.org> <CAJ-FndAkZrt1qAQHOR6-bO1JN5KoTsQ7T4MDkcjkQge7dcs0dw@mail.gmail.com>
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On 5/13/13 2:59 PM, Attilio Rao wrote: > 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. Bah, I misread the diff and thought that the change to vm_phys_alloc_contig() was changing alloc_pages_domain(), my bad. -- John Baldwinhelp
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