Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Spectre mitigations murder userspace performance

robert.ocallahan.org

Post reply on HN
Print view View original

131–140 of 294 posts

Re: Spectre mitigations murder userspace performance

#131

Post by hutzlibu »

jacquesm wrote: post #58
dustingetz wrote: post #29

Earlier quoted context omitted.

your desktop is already rooted by Zoom

And teams. And all that software that you used to be able to use that you have to make exceptions for so that in the end you end up forgetting to re-enable some critical part of the windows scareware implementation. Seriously: try installing Firefox on Windows 10 (I had to do this recently, I have now one computer in the house on Win 10 due to a hard requirement for some software/hardware combo), and you'll see Micro…

" Has there ever been a large company in IT that didn't turn absolutely evil as soon as the opportunity presented itself?"

I like nuances, though. "absolute evil" is a bit strong.

There were companies who were engaged with enslaving people and working them to death. (some still are)

I am no fan of googles development, but absolute evil leaves no room to describe other companies who are actually worse.

Re: Spectre mitigations murder userspace performance

#132

Post by mhh__ »

pjc50 wrote: post #27
infogulch wrote: post #15

Earlier quoted context omitted.

I suspect our heavy reliance on speculative execution is just a local optimum, and we can grow out of it by providing the processor more information about the data flow, making memory access more explicitly asynchronous, and simplifying the hot paths. I like the way the mill approaches these architectural problems.

Is the Mill dead? I've not seen the regular flow of HN posts about it recently. Everyone got excited about RISC-V instead.

They're still going - Ivan said on their forum that they were planning on going full steam ahead last summer, but scuppered by lockdown. I don't totally buy that, but that's the story.

Re: Spectre mitigations murder userspace performance

#133

Post by wizzwizz4 »

teddyh wrote: post #91
cj wrote: post #64

Earlier quoted context omitted.

“Close browser tab” - immediately exits a Google Meet. Closing a Zoom/Webex meeting, who knows since it’s still running in the background. I also like meetings sandboxed in a browser so weird things like “automatically take control of your screen and maximize window” doesn’t happen when someone in a Zoom meeting starts sharing their screen. Even at the expense of more CPU.

> “Close browser tab” - immediately exits a Google Meet. How would you know? Or, put another way: Why don’t you want to trust Google Meet, but apparently want to trust Google Chrome?

Meet isn't much integrated into Chrome, so absent a Chrome bug, closing Meet stops running Meet code, so stops the meeting. “Closing” Zoom relies on Zoom detecting the closure and stopping the meeting.

It's not about spying from the software authors (having these softwares on your computer makes that impossible to defend against), but about knowing whether the people you were just talking to still have access to your camera and microphone feeds.

Re: Spectre mitigations murder userspace performance

#134

Post by hinkley »

Filligree wrote: post #47
emilfihlman wrote: post #42

Can we have syscall chaining finally? Please? There is literally no reason why we couldn't have it.

Do you mean io_uring?

Doesn’t that address fanout, not chaining?

Chaining RPC calls requires something more sophisticated.

Re: Spectre mitigations murder userspace performance

#135

Post by desert_boi »

jodrellblank wrote: post #106
lumost wrote: post #89

Earlier quoted context omitted.

has there been any research on what hardware changes would be necessary to reclaim performance? I've noticed extreme stutter events on desktop OSX for the last 2 years. Would be curious if its related.

Seems like there’s a lot of people with stuttering macOS https://apple.stackexchange.com/questions/245429/cursor-free... USB-C and USB 3.0 devices are one common cause, Bluetooth mouse interference by USB another, and external monitors after sleep/wake another.

https://apple.stackexchange.com/questions/407177/windowserve... started happening in Big Sur to me.

Re: Spectre mitigations murder userspace performance

#136

Post by KronisLV »

alisonkisk wrote: post #119
dijit wrote: post #107

Earlier quoted context omitted.

I use a browser called Qutebrowser which doesn't have a noscript addon; but I can disable javascript loading on a domain level. However, overall I can tell you for absolute certain: if you have JS partially disabled things break in non-obvious ways and I find myself playing whack-a-mole with allowing various domains to load javascript to get the page working. I'm pretty certain you do also, because it's basically imp…

I like this breakage because it makes me unhappy with the website and less likely to use it -- the immune system is working as it should.

That's probably a good approach for random news sites and such, much less so when your internet banking and even online shopping sites require JS on.

Re: Spectre mitigations murder userspace performance

#137

Post by eloff »

jacquesm wrote: post #63
eloff wrote: post #53

Earlier quoted context omitted.

They tried. The V8 team eventually gave up and said it was unwinnable. What they did do is move tabs to their own process so they can take average of the operating systems protections. Yes you can read the memory of the process hosting the JavaScript, but now there isn't anything interesting in it. Google's security team released a proof of concept attack that can read the memory in the renderer in many systems.

average -> advantage

Man mobile keyboards suck. Any idiot knows the word average doesn't work there (at minimum you'd have to preface it with the word "the"), so why can't my keyboard run an ML model that's not an idiot?

Re: Spectre mitigations murder userspace performance

#138

Post by foobiekr »

lumost wrote: post #89
neilsimp1 wrote: post #2

`mitigations=off` in your GRUB_CMDLINE_LINUX_DEFAULT to disable Spectre/Meltdown mitigations, in case anyone is wondering. This page has a pretty decent write-up on it: https://leochavez.org/index.php/2020/11/16/disabling-intel-a... .

has there been any research on what hardware changes would be necessary to reclaim performance? I've noticed extreme stutter events on desktop OSX for the last 2 years. Would be curious if its related.

You can turn macOS into Windows 3.1 reading a floppy by mounting an SMB share with a ton of small files and running an rclone sync between it and an external drive that has previously completed a sync. The stat() operations make the kernel go crazy. It’s the most appalling thing I’ve seen and has been broken like this since Catalina where it arrived as a massive performance regression.

Re: Spectre mitigations murder userspace performance

#139

Post by netr0ute »

diegocg wrote: post #95
netr0ute wrote: post #21

Earlier quoted context omitted.

That's what JavaScript blockers like NoScript and uBlock Origin are for.

Ad blockers can not know if a JavaScript algorithm is dangerous or not

People do, and the JS algorithms will get added to adblocker lists in no time.

Re: Spectre mitigations murder userspace performance

#140

Post by porphyra »

dijit wrote: post #14
neilsimp1 wrote: post #2

`mitigations=off` in your GRUB_CMDLINE_LINUX_DEFAULT to disable Spectre/Meltdown mitigations, in case anyone is wondering. This page has a pretty decent write-up on it: https://leochavez.org/index.php/2020/11/16/disabling-intel-a... .

I love that this is a toggle like this, having control of my system is why I love Linux. But I must caution desktop users against doing this for performance, it's _much_ better to have some kind of build server somewhere else with this kernel flag than to run it on your desktop. Why? because your desktop executes untrusted and rather arbitrary code pretty often, not just in the form of Javascript but that's the large…

Phoronix has comprehensive benchmarks on the impact of spectre mitigations if you want to find out how much of a difference it will actually make before exposing your system:

https://www.phoronix.com/scan.php?page=search&q=Spectre

Post reply on HN