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On 08/23/2018 06:15 AM, dick balaska wrote:
> On 08/23/2018 06:07 AM, dick balaska wrote:
>
>>
>>
https://www.bestbuy.com/site/dell-inspiron-desktop-intel-core-i5-12gb-memory-1tb-hard-drive-black-with-silver-trim/6228201.p?skuId=6228201
>>
>
> "Smart six-core, twelve-way processing performance"
> No it doesn't.
>
> $ cat /proc/cpuinfo
> vendor_id : GenuineIntel
> model name : Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz
> cpu MHz : 3799.999
> cache size : 9216 KB
> siblings : 6
> cpu cores : 6
>
>
> My 4 core / 8 thread i7
> $ cat /proc/cpuinfo
> vendor_id : GenuineIntel
> model name : Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> cpu MHz : 3492.055
> cache size : 8192 KB
> siblings : 8
> cpu cores : 4
>
I came across an article a while back about Intel dropping
hyper-threading in favor of cores at the lower end. Looks like yours is
one of those processors!
More cores is better for POV-Ray so this no threading more cores change
helps us - and especially in v3.8 over v3.7 given it's threads > cores
performance has slowed more than threads <= cores has (6% vs about 3%
last I did any measures).
Note that your i5-8400 has a turbo frequency of 'up to' 4GHz throttled
by temperature. Many other processors have the turbo option too though
often it's not a much higher frequency than the normal in older
generations. If turbo mode is not off turned off in bios, performance
measures to 'clock time' can be all over the place - better to measure
hardware cycles and even there you need to be sure you are not thrashing
your caches with other work for example.
My little i3-4130 doesn't have the turbo mode which makes timing
relative to the 'clock' a little more reliable.
Well, excepting starting earlier this year when measured time seemed to
get more unstable. Has me wondering about possible impacts for some of
those security patches for metldown and specter exposures - but I've
done no digging. Might be I'm just timing different features of POV-Ray
of late that have different register and cache usage patterns.
Aside: This is the first I've noticed /proc/cpuinfo having bug
information. Mine shows:
bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf
Any of those gone on your i5-8400?
Bill P.
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