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Groups > comp.os.linux.advocacy > #448151

A page fault can cost ONE MILLION CLOCK CYCLES.

From Jeff-Relf.Me @.
Message-ID <Jeff-Relf.Me@Apr.11--0.09pm.Seattle.2018> (permalink)
References <padcgh03u@news4.newsguy.com> <paiku402uik@news7.newsguy.com> <sa0b803g.aho93@rooftop.invalid> <pakkh202pf6@news4.newsguy.com> <9a0b80tr.ahu34@rooftop.invalid>
Newsgroups comp.os.linux.advocacy
Subject A page fault can cost ONE MILLION CLOCK CYCLES.
Organization usenet-news.net
Date 2018-04-11 12:09 -0700

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> My guess is that the option predates L3 cache and refers
> to highest level cache, whatever it might be called.  
> 
> Some CPUs have l4 cache now, and in that case the l2 param
> might refer to l4.

My CPU, the i7-5775c, has a 128 MegaByte L-4 cache, 
a.k.a. "Crystal Well" ( 1.8 GigaHz eDRAM ).

Fabian got ( pa92ch01sun@news1.newsguy.com ):

  Loop 1: 3.01377 seconds
  Loop 2:  .11461 seconds

I get:

  Loop 1: 2.434 seconds      
  Loop 2:  .089 seconds   ( 2.434 / .089 =  27 )

Owl got ( 9a0b773q.u9b@rooftop.invalid ):

  Loop 1: 4.64766 seconds  Minor page faults: 262,211
  Loop 2:  .32333 seconds  Minor page faults: 262,215  [ Why more ? ]

Quoting "Docs.MicroSoft.COM/en-us/cpp/build/reference/Tips-for-Improving-Time-Critical-Code"

  A CPU cache hit can cost your program 10 to 20 clock cycles. 
  An external cache hit can cost 20 to 40 clock cycles.
  A page fault can cost ONE MILLION CLOCK CYCLES.

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Thread

Gentoo is *BEST* GNU/Linux "F. Russell" <fr@random.info> - 2018-04-08 15:29 +0000
  Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-08 10:51 -0700
  Re: Gentoo is *BEST* GNU/Linux Melzzzzz <Melzzzzz@zzzzz.com> - 2018-04-08 19:36 +0000
    Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-08 12:41 -0700
    Re: Gentoo is *BEST* GNU/Linux "F. Russell" <fr@random.info> - 2018-04-08 20:03 +0000
      Re: Gentoo is *BEST* GNU/Linux Melzzzzz <Melzzzzz@zzzzz.com> - 2018-04-08 20:22 +0000
        Re: Gentoo is *BEST* GNU/Linux "F. Russell" <fr@random.info> - 2018-04-08 21:06 +0000
      Re: Gentoo is *BEST* GNU/Linux owl <owl@rooftop.invalid> - 2018-04-08 21:02 +0000
        Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-08 14:31 -0700
        Re: Gentoo is *BEST* GNU/Linux "F. Russell" <fr@random.info> - 2018-04-08 22:03 +0000
          Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-08 15:18 -0700
            Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-08 20:00 -0700
          Re: Gentoo is *BEST* GNU/Linux owl <owl@rooftop.invalid> - 2018-04-08 23:47 +0000
            Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-08 17:09 -0700
  Re: Gentoo is *BEST* GNU/Linux "F. Russell" <fr@random.info> - 2018-04-10 15:23 +0000
    Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-10 11:35 -0700
    Re: Gentoo is *BEST* GNU/Linux owl <owl@rooftop.invalid> - 2018-04-10 20:31 +0000
      Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-10 21:53 -0700
      Re: Gentoo is *BEST* GNU/Linux "F. Russell" <fr@random.info> - 2018-04-11 09:29 +0000
        Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-11 03:35 -0700
        Re: Gentoo is *BEST* GNU/Linux owl <owl@rooftop.invalid> - 2018-04-11 12:21 +0000
          Re: Gentoo is *BEST* GNU/Linux Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-11 06:43 -0700
          A page fault can cost ONE MILLION CLOCK CYCLES. Jeff-Relf.Me  @. - 2018-04-11 12:09 -0700
            Re: A page fault can cost ONE MILLION CLOCK CYCLES. Melzzzzz <Melzzzzz@zzzzz.com> - 2018-04-11 19:25 +0000
              Re: A page fault can cost ONE MILLION CLOCK CYCLES. Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-12 02:24 -0700
              Re: A page fault can cost ONE MILLION CLOCK CYCLES. Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-12 06:51 -0700
              365 Million L3 Misses. Jeff-Relf.Me  @. - 2018-04-14 07:58 -0700
                Re: 365 Million L3 Misses. Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-14 08:48 -0700
            Re: A page fault can cost ONE MILLION CLOCK CYCLES. Steven Petruzzellis <frelwizzen@gmail.com> - 2018-04-11 21:59 -0700
        Re: Gentoo is *BEST* GNU/Linux owl <owl@rooftop.invalid> - 2018-04-11 13:14 +0000

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