Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs

From	"J.O. Aho" <user@example.net>
Newsgroups	alt.os.linux, comp.os.linux.misc
Subject	Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs
Date	2018-11-18 22:27 +0100
Message-ID	<g5e3q5Ffs9kU1@mid.individual.net> (permalink)
References	<psntul$etc$1@news.mixmin.net> <g5a7ouFjvp8U1@mid.individual.net> <rv65cf-i69.ln1@Telcontar.valinor> <87ftvzgbsi.fsf@LkoBDZeT.terraraq.uk> <3ct8cf-dgg.ln1@Telcontar.valinor>

Cross-posted to 2 groups.

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On 11/18/18 9:06 PM, Carlos E.R. wrote:
> On 17/11/2018 12.53, Richard Kettlewell wrote:
>> "Carlos E.R." <robin_listas@es.invalid> writes:
>>> On 17/11/2018 11.10, J.O. Aho wrote:
>>>> On 11/17/18 3:21 AM, Nomen Nescio wrote:
>>>>> <https://www.phoronix.com/scan.php?page=article&item=linux-420-bisect&num=1>
>>>>>
>>>>
>>>> And it will run slower in the future as more and more serious security
>>>> vulnerabilities are found in intel hardware which then has to be fixed
>>>> in software.
>>>>
>>>> The only CPU which seems to have been safe to use has been RISC-V, just
>>>> hope we will see desktop grade CPU's soon.
>>
>> Lots of other older CPUs are also immune to this attack class, they’re
>> just very slow by modern standards.
>>
>>> Well, possibly the smaller the instruction set, the less danger of
>>> fucking up.
>>
>> It’s not really anything to do with the size of the instruction set. The
>> microarchitectural attacks are essentially about how the instruction set
>> is implemented efficiently (mostly in time terms although the AVX warmup
>> sidechannel depends on a power usage optimization).
> 
> I don't mean exactly that the size is involved, but that fewer
> instructions and less complex instructions probably produce less
> complexity of the chip itself and fewer chances of errors. The
> complexity goes to the kernel and applications instead, but these can be
> corrected, whereas the cpu itself can't (some parts can, firmware updates).

It's been more about the speculative execution than the instructions
themselves, in Intel's drive to have the "fastest" CPU's they made
shortcuts which resulted in that their CPU's have been more vulnerable
to Meltdown and Spectre than other CPU's from AMD and Arm-family, which
both have been affected by the vulnerabilities too.

The whole idea with speculative execution is that it's better to start
doing something that seems to be needed to be done in the future, in
worst case you just throw away the result if not needed, but as the
thrown away data ain't protected it's possible to in one way or another
to get access to the data. If you disable the speculative execution,
then the CPU will do it's job slower and some of the fixes are to
disable the use of speculative execution and the more Intel related such
you find, the risk is that it will execute things even slower unless you
are prepared to have an insecure system.

-- 

 //Aho

Thread

Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Nomen Nescio <noreply@mixnym.net> - 2018-11-16 20:21 -0600
  Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "J.O. Aho" <user@example.net> - 2018-11-17 11:10 +0100
    Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "Carlos E.R." <robin_listas@es.invalid> - 2018-11-17 11:26 +0100
      Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Richard Kettlewell <invalid@invalid.invalid> - 2018-11-17 11:53 +0000
        Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "Carlos E.R." <robin_listas@es.invalid> - 2018-11-18 21:06 +0100
          Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Paul <nospam@needed.invalid> - 2018-11-18 15:46 -0500
            Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Bud Frede <frede@mouse-potato.com> - 2018-11-24 09:07 -0500
          Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "J.O. Aho" <user@example.net> - 2018-11-18 22:27 +0100
          Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Richard Kettlewell <invalid@invalid.invalid> - 2018-11-19 08:27 +0000
          Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-11-19 18:33 +0000
            Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "J.O. Aho" <user@example.net> - 2018-11-19 21:02 +0100
              Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-11-20 04:46 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "J.O. Aho" <user@example.net> - 2018-11-20 06:59 +0100
            Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs not@telling.you.invalid (Computer Nerd Kev) - 2018-11-19 21:58 +0000
              Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2018-11-19 17:27 -0500
            Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2018-11-19 17:37 -0500
              Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Richard Kettlewell <invalid@invalid.invalid> - 2018-11-20 10:10 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Andreas Kohlbach <ank@spamfence.net> - 2018-11-20 15:51 -0500
              Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs not@telling.you.invalid (Computer Nerd Kev) - 2018-11-20 21:31 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Rich <rich@example.invalid> - 2018-11-20 23:14 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-11-21 06:50 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Paul <nospam@needed.invalid> - 2018-11-21 04:24 -0500
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Richard Kettlewell <invalid@invalid.invalid> - 2018-11-21 10:56 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Rich <rich@example.invalid> - 2018-11-21 12:22 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Richard Kettlewell <invalid@invalid.invalid> - 2018-11-21 13:24 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-11-21 22:08 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs William Unruh <unruh@invalid.ca> - 2018-11-21 23:53 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-11-24 11:46 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs William Unruh <unruh@invalid.ca> - 2018-11-24 13:53 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-11-24 18:39 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Andreas Kohlbach <ank@spamfence.net> - 2018-11-24 15:47 -0500
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-11-25 07:51 +0000
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Andreas Kohlbach <ank@spamfence.net> - 2018-11-25 16:08 -0500
                Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Rich <rich@example.invalid> - 2018-11-24 15:24 +0000
          Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Soviet_Mario <SovietMario@CCCP.MIR> - 2018-11-30 11:32 +0100
            Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs The Natural Philosopher <tnp@invalid.invalid> - 2018-12-01 05:13 +0000
    Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "Anonymous Remailer (austria)" <mixmaster@remailer.privacy.at> - 2018-11-18 06:23 +0100
      Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Jens Stuckelberger <Jens_Stuckelberger@nowhere.net> - 2018-11-19 19:06 +0000
        Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Anonymous <anonymous@hoi-polloi.org> - 2018-11-19 21:44 +0100
          Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Nomen Nescio <nobody@dizum.com> - 2018-11-20 10:19 +0100
        Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Dave Froble <davef@tsoft-inc.com> - 2018-11-19 18:44 -0500
          Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs kludge@panix.com (Scott Dorsey) - 2018-11-19 19:00 -0500
            Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Bobbie Sellers <bliss@mouse-potato.com> - 2018-11-26 20:40 -0800
        Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Nomen Nescio <nobody@dizum.com> - 2018-11-20 10:09 +0100
    Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs fr314159@gmail.com - 2018-11-28 07:26 -0800
      Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Jasen Betts <jasen@xnet.co.nz> - 2018-11-29 19:45 +0000
        Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs Melzzzzz <Melzzzzz@zzzzz.com> - 2018-11-29 20:21 +0000
        Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs "F. Russell" <fr@random.info> - 2018-11-29 20:26 +0000

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