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

From	The Natural Philosopher <tnp@invalid.invalid>
Newsgroups	alt.os.linux, comp.os.linux.misc
Subject	Re: Linux 4.20 is Running Slower Than 4.19 On Intel CPUs
Date	2018-12-01 05:13 +0000
Organization	A little, after lunch
Message-ID	<ptt59n$j70$1@dont-email.me> (permalink)
References	(1 earlier) <g5a7ouFjvp8U1@mid.individual.net> <rv65cf-i69.ln1@Telcontar.valinor> <87ftvzgbsi.fsf@LkoBDZeT.terraraq.uk> <3ct8cf-dgg.ln1@Telcontar.valinor> <ptr3j3$jtk$1@dont-email.me>

Cross-posted to 2 groups.

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On 30/11/2018 10:32, Soviet_Mario wrote:
> On 18/11/18 21:06, 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, 
> 
> I was having the same idea but with no clue of the reason of this ... 
> could you delve a bit deeper in this aspect (= why hw simplification 
> would necessarily imply sw complication ?) ?
> I mean, I'm quite convinced that LONGER sw (in binary outline) is a 
> result of RISC instead of CISC, but I'm unsure about the greater 
> complexity (as I don't have a suitable definition of complexity, or at 
> least not a quantitative one)
> 
> Another thing complicates my view (and this even from an HW point of 
> view) : some times simplified layers imply more layers to get an high 
> level task out of the "iron".
> 
> So I'm wondering whether a reduced set of instructions is just a mean of 
> MOVING complexity elsewhere and distribute it differently (where with 
> "elsewhere" I don't necessarily mean from HW -> to SW, but maybe also 
> from the CPU to other features of the overall architecture).
> 
> P.S. I'm not questioning about the proved less vulnerable risc 
> architecture, just trying to understand why
> 
> 
AIUI which isnt so much these days all CISC  chips are at core RISC and 
they INTERPRET the instruction sets via microcode .


> 
>> but these can be
>> corrected, whereas the cpu itself can't (some parts can, firmware 
>> updates).
>>
>> Just an educated guess :-)
>>
>>
> 
> 


-- 
Climate Change: Socialism wearing a lab coat.

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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