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Disable Meltdown/Spectre to regain performance
Disable Meltdown/Spectre to regain performance
Hi,
Because of the current Intel CPU security hole issue, there is a patch expected which slows down the system performance.
Reading some articles, they say that in order to recover the lost performance before the security paches, You need to disable the PTI(Page Table Isolation).
https://www.stevenrombauts.be/2018/02/h ... chmarking/
So would be theses considerations ok?.:
- For Spectre patches lost performance >> uninstall firmware-intel or install version before Spectre pacthes
- For Meltdown patches lost performance >> Disable PTI (nopti pti=off)
Ive got into this solution, Add the following to the end of your kernel argument in grub:
spectre_v2=off nopti pti=off
is it right?? , any additional consideration?
Thanks.
Because of the current Intel CPU security hole issue, there is a patch expected which slows down the system performance.
Reading some articles, they say that in order to recover the lost performance before the security paches, You need to disable the PTI(Page Table Isolation).
https://www.stevenrombauts.be/2018/02/h ... chmarking/
So would be theses considerations ok?.:
- For Spectre patches lost performance >> uninstall firmware-intel or install version before Spectre pacthes
- For Meltdown patches lost performance >> Disable PTI (nopti pti=off)
Ive got into this solution, Add the following to the end of your kernel argument in grub:
spectre_v2=off nopti pti=off
is it right?? , any additional consideration?
Thanks.
bester69 wrote:STOP 2030 globalists demons, keep the fight for humanity freedom against NWO...
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Re: Disable Meltdown/Spectre to regain performance
Now you're being silly. Why compromise security for an imperceptible performance boost? Have you tested how much difference it makes?
The Meltdown/Spectre patches were added months ago. Personally I noticed no difference.
The Meltdown/Spectre patches were added months ago. Personally I noticed no difference.
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Those who have lost data
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Re: Disable Meltdown/Spectre to regain performance
the intel firmware has nothing to do with linux kernel's PTI.
(i think intel "promised" to "fix" the issue via firmware, but it seems linux kernel devs don't trust that so much)
i noticed a significant performance drop after PTI was first introduced into the kernel, but idk - either i got used to it, or it got better in subsequent kernel verisons.
i am now on 4.14.51.
(i think intel "promised" to "fix" the issue via firmware, but it seems linux kernel devs don't trust that so much)
i noticed a significant performance drop after PTI was first introduced into the kernel, but idk - either i got used to it, or it got better in subsequent kernel verisons.
i am now on 4.14.51.
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Re: Disable Meltdown/Spectre to regain performance
Just wait--BSD has disabled hyperthreading in their kernels in response to a yet undisclosed Intel vulnerability scheduled to be announced at the Black Hat conference in August. That drops performance by at least 20% on affected Intel CPUs...including mine.
Intel is rumored to be trying to come with a fix that won't affect performance as much, but the bad news just keeps coming.
Intel is rumored to be trying to come with a fix that won't affect performance as much, but the bad news just keeps coming.
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Re: Disable Meltdown/Spectre to regain performance
The OpenBSD devs believe that Intel's technique leaves the door open for an entire class of new vulnerabilities, not just one:stevepusser wrote:Just wait--BSD has disabled hyperthreading in their kernels in response to a yet undisclosed Intel vulnerability
https://marc.info/?l=openbsd-cvs&m=152943660103446&w=2
I've been running without SMT in OpenBSD since the original commit and I can notice very little differencestevepusser wrote:That drops performance by at least 20% on affected Intel CPUs
Theo even suggests that the box may run faster without hyperthreading:
https://marc.info/?l=openbsd-misc&m=152938776411086&w=2
deadbang
Re: Disable Meltdown/Spectre to regain performance
My system is very old spec's, and Im still using 4.4.39 cos performance and graphical feelings, I dont need this kind of security patches in my computer, none is gonna knock at my door..debiman wrote:the intel firmware has nothing to do with linux kernel's PTI.
(i think intel "promised" to "fix" the issue via firmware, but it seems linux kernel devs don't trust that so much)
i noticed a significant performance drop after PTI was first introduced into the kernel, but idk - either i got used to it, or it got better in subsequent kernel verisons.
i am now on 4.14.51.
but other day I was thinking perhaps if i disabled PTI I might be able to move on to new kernels and keep similar or improve performance.. I did it with PTI and tried with last 4.4.x and with 4.17.x and It wasnt the case, I think from some old version on, they introduced something in kernel that makes my old computer feel badly different, I feel it like if graphics were using something like VAAPI with a litle smooth graphical response, Its an annoy and artificial feeling I cant feed up with. I cant explain it, but every kernel i try i come back to 4.4.39.
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Re: Disable Meltdown/Spectre to regain performance
It is a basic feature of human psychology called confirmation bias:bester69 wrote:I cant explain it
https://en.wikipedia.org/wiki/Confirmation_bias
This is why we have benchmarks
deadbang
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Re: Disable Meltdown/Spectre to regain performance
Great Link, I like this part:
Explanations for the observed biases include wishful thinking and the limited human capacity to process information. Another explanation is that people show confirmation bias because they are weighing up the costs of being wrong, rather than investigating in a neutral, scientific way. However, even scientists can be prone to confirmation bias.[2]
Confirmation biases contribute to overconfidence in personal beliefs and can maintain or strengthen beliefs in the face of contrary evidence. Poor decisions due to these biases have been found in political and organizational contexts.[3][4]
"What we expect you have already Done"
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What Does a Parrot Know About PTSD?
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Re: Disable Meltdown/Spectre to regain performance
Well, I can't turn it off on my machine, but I know it can on some computers. Is there a kernel boot flag to do this? Let's see some benchmarks! Though I'm sure Phoronix will have some, too.Head_on_a_Stick wrote:The OpenBSD devs believe that Intel's technique leaves the door open for an entire class of new vulnerabilities, not just one:stevepusser wrote:Just wait--BSD has disabled hyperthreading in their kernels in response to a yet undisclosed Intel vulnerability
https://marc.info/?l=openbsd-cvs&m=152943660103446&w=2
I've been running without SMT in OpenBSD since the original commit and I can notice very little differencestevepusser wrote:That drops performance by at least 20% on affected Intel CPUs
Theo even suggests that the box may run faster without hyperthreading:
https://marc.info/?l=openbsd-misc&m=152938776411086&w=2
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Re: Disable Meltdown/Spectre to regain performance
Very intersting and complex subject, Dont think i didnt thought of that, I started to think perhaps my mind was tricking me , So I tried some kernels for a three , four days period, and there was something I didnt feel confortable.. I can swear you I dont need benchmarks to feel if it performance worse, similar or better, we're talking about and old low spec laptop where minimal differences can be felt it easily.Head_on_a_Stick wrote:It is a basic feature of human psychology called confirmation bias:bester69 wrote:I cant explain it
https://en.wikipedia.org/wiki/Confirmation_bias
This is why we have benchmarks
To me, happend the same with some interestings beliefs, I do know they're "truth" cos the model that explains them
fits an empirical reality according to my experiences life. Im talking about two different and important litle known concepts: "reactive mind" and "organic portals"..I share that "bias confimation" with anyone of you that might be interested.
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Re: Disable Meltdown/Spectre to regain performance
Have you triedstevepusser wrote:Is there a kernel boot flag to do this?
Code: Select all
noht
The framerate in games/openarena is unchanged, as are the render times in graphics/blender.Let's see some benchmarks!
deadbang
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Re: Disable Meltdown/Spectre to regain performance
The noht flag doesn't have any effect, at least on backported Debian experimental 4.17.2 and Liquorix 4.16-16.3 kernels...
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Re: Disable Meltdown/Spectre to regain performance
Yes, my apologies, I should have tested that before postingstevepusser wrote:The noht flag doesn't have any effect
I can only find nosmt but it doesn't apply to x86_64 (amd64), unfortunately:
https://github.com/torvalds/linux/blob/ ... .txt#L2687
deadbang
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Re: Disable Meltdown/Spectre to regain performance
This works on my ThinkPad X201 with the stock Debian stable kernel:stevepusser wrote:Is there a kernel boot flag to do this?
Code: Select all
nosmp
deadbang