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Groups > alt.os.linux > #51792
| 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 | 2018-11-24 18:39 +0000 |
| Organization | A little, after lunch |
| Message-ID | <ptc5ts$b84$1@dont-email.me> (permalink) |
| References | (10 earlier) <87sgzud0mz.fsf@LkoBDZeT.terraraq.uk> <pt4l0d$r33$1@dont-email.me> <pt4r58$rne$1@dont-email.me> <ptbdls$udo$1@dont-email.me> <ptbl5c$22p$1@dont-email.me> |
Cross-posted to 2 groups.
On 24/11/2018 13:53, William Unruh wrote: > On 2018-11-24, The Natural Philosopher <tnp@invalid.invalid> wrote: >> On 21/11/2018 23:53, William Unruh wrote: >>> On 2018-11-21, The Natural Philosopher <tnp@invalid.invalid> wrote: >>>> On 21/11/2018 13:24, Richard Kettlewell wrote: >>>>> Rich <rich@example.invalid> writes: >>>>>> In comp.os.linux.misc The Natural Philosopher <tnp@invalid.invalid> wrote: >>>>>>> Intersting that people differentiate between 'speculative execution' and >>>>>>> 'caching'. >>>>>>> >>>>>>> Or is caching 'speculative memory access' as opposed to 'speculative >>>>>>> execution'? >>>>>> >>>>>> You could call it (caching) that (speculative memory access). >>>>>> >>>>>> Caching works on the principal that most programs often access memory >>>>>> addresses that are nearby other memory addresses previously accessed by >>>>>> the same program. I.e., consider walking an array (X[0] ... X[100]) >>>>>> and doing something. First access is to X[0], second to X[1], third to >>>>>> X[2] and so on. Caching works because when the program reads X[0] the >>>>>> cache actually reads in memory that holds X[0]...X[10]. So now >>>>>> accesses to X[1]...X[10] happen from the cache instead of each directly >>>>>> from main memory. >>>>> >>>>> That’s certainly a useful outcome of the way memory access works, but >>>>> it’s not inherent to caching. A CPU could (hypothetically) cache >>>>> individual words and still get a (smaller) performance improvement from >>>>> the cache hits. Moreover in the context of this thread it’s the caching >>>>> as such, rather than the bulk reads, that leads to the cache being >>>>> usable as a communication channel. >>>>> >>>>> Analogously, disk reads typically happen in 512-byte or 4096-byte blocks >>>>> (at a minimum), but when we talk about filesystem caching, we don’t mean >>>>> that bulk I/O, we mean the OS keeping large numbers of those blocks in >>>>> RAM to avoid having to read them again in the near future. >>>>> >>>>> At any rate conflating caching with speculative execution is a >>>>> non-starter. >>>>> >>>> My statement was more semantic than technical >>> >>> ???? It is not correct sematically (whatever you mean by that) either. >> >> Oh it is. >> >> Speculative executins get stored - cached in case trhey are needed > > The point of speculative execution is not storage, but execution. Yes, > the result gets stored in the cpu but that storage is not the purpose. > The purpose is the exectution of the instructions that are not yet > called for. > > >> Memory contents get strored - cached - in case they are needed >> Disc sectors get stored - cached - ion case they are needed >> >> speculative execution/speculative memory read/speculative disc read. >> >> I dont see any difference philosophicallyu - just at implementation level. > > An example of why "Philosophical" often gets such a bad rap. >> Wj example of why tekky pedants get such a bad rap >> >>>> >>>> >> >> -- "I guess a rattlesnake ain't risponsible fer bein' a rattlesnake, but ah puts mah heel on um jess the same if'n I catches him around mah chillun".
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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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