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Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

bugzilla.mozilla.org

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Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#331

Post by acomjean »

grugagag wrote: post #260
acomjean wrote: post #232

Earlier quoted context omitted.

I switched to linux. I like it and haven't really had any issues to speak of. Not with sound, video, wifi or any of the other things people complain about. My fan went, but likely it was a pet fur issue, and easy to fix... I'm not an admin. I know how to use the command line, and how to use it as a work machine. Really my experience over the past 3 years, its been as trouble free as my Mac used to be. It really is th…

Can you hybernate your system without issues?

it "suspends" fine. I have 3 options, suspend, off and reboot. I usually suspend overnight. Sometimes I turn it off. It boots super fast anyway.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#332

Post by mr_toad »

dist-epoch wrote: post #120
arnaudsm wrote: post #40

Quick napkin math of the wasted power : Firefox has ~300e6 users, let's assume the bug wasted 5 extra watts 4 hours a day. That's 250 megawatts saved, the equivalent of an average coal power plant. Because some Microsoft engineer missed a bug.

> That's 250 megawatts saved, the equivalent of an average coal power plant. Because some Microsoft engineer missed a bug. Are you sure you want to invoke this logic? Because following it through imagine the energy savings if Firefox users switched to Chrome.

> Are you sure you want to invoke this logic? Because following it through imagine the energy savings if Firefox users switched to Chrome.

And then imagine Safari on an M1.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#333

Post by acomjean »

JadeNB wrote: post #304
acomjean wrote: post #232

Earlier quoted context omitted.

I switched to linux. I like it and haven't really had any issues to speak of. Not with sound, video, wifi or any of the other things people complain about. My fan went, but likely it was a pet fur issue, and easy to fix... I'm not an admin. I know how to use the command line, and how to use it as a work machine. Really my experience over the past 3 years, its been as trouble free as my Mac used to be. It really is th…

> I switched to linux. I like it and haven't really had any issues to speak of. Not with sound, video, wifi or any of the other things people complain about. What's your machine+distro?

I'm running a last gen pangolin, (AMD 5700U). Pop OS. I don't do anything too crazy. I develop on JetBrains I did keep it awake for 3 days doing some genetics work I usually do on a cluster. Its fast, quiet and decent on battery. AMD on the notebook is really impressive.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#334

Post by bmicraft »

waz0wski wrote: post #323
cronix wrote: post #143

If you're on a Mac and using FF (probably not FF specific), turning off "ambient mode" in youtube can save 30% cpu. I just found this out while searching why FF was taking 90% of my cpu while watching youtube videos in normal mode, but went down to 40% use if viewing in full screen. Turns out that this youtube "ambient mode" was the culprit. My lap is now cooler and the fan doesn't turn on anymore. I wonder how much…

Or stop using the crap YT frontent entirely - https://yewtu.be Run your own alternate frontend - https://github.com/iv-org/invidious

That site doesn't even seem to support anything over 720p, so much for crap

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#335

Post by Dalewyn »

dgellow wrote: post #35

> mpengine.dll version 1.1.20200.4 was released on April 4, so the fix should be available for everybody now. See the end of comment 91 to know what version you are using. Also, the latest discoveries in bug 1822650 comment 6 suggest that we can go even further down in CPU usage, with all antivirus software this time, not just Windows Defender. Really nice to see open collaboration between Mozilla and Microsoft devel…

I'll note that mpengine.dll was updated for me on Windows 11 Pro 21H2 in spite of my blocking autoupdates via Group Policy.

To be clear: I'm aware Windows Defender updates itself independently of Windows Update, and I actually don't mind and even appreciate this behaviour since Defender updates almost always aren't intrusive unlike the rest of Windows Update.

Just an FYI for people with similar configs.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#336

Post by zimmund »

cronix wrote: post #143

If you're on a Mac and using FF (probably not FF specific), turning off "ambient mode" in youtube can save 30% cpu. I just found this out while searching why FF was taking 90% of my cpu while watching youtube videos in normal mode, but went down to 40% use if viewing in full screen. Turns out that this youtube "ambient mode" was the culprit. My lap is now cooler and the fan doesn't turn on anymore. I wonder how much…

To be fair this wastes CPU cycles in all platforms. And it probably took more human effort than keeping Google Reader alive FFS.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#337

Post by LegitShady »

duttonw wrote: post #298
LegitShady wrote: post #280

Earlier quoted context omitted.

I dont have that option. firefox on windows 10.

only shows up when in 'dark mode'.

this makes sense. I stopped doing per site dark mode and just use the darkreader extension to make everything dark mode, so the option never appears.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#338

Post by LegitShady »

cronix wrote: post #303
LegitShady wrote: post #282

Earlier quoted context omitted.

its not there for me. I dont see it in any settings anywhere.

Is Dark Mode in either your OS or Youtube turned on? It's not an option unless you're in DM.

I stopped doing per-site dark mode and just use the darkreader extension, which is why this option was never there. I call it a win to not deal with per site settings.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#339

Post by jesse__ »

shadowgovt wrote: post #208
jesse__ wrote: post #116

Earlier quoted context omitted.

I'm not sure how you can possibly qualify VirtualProtect as "an expensive platform feature". Looking at the operation that VirtualProtect actually has to perform, from first principals, it should be one of the cheapest syscalls in the entire kernel. The bug was that ETW (in the antivirus process) was doing something braindead; zeroing a megabyte of memory unnecessarily every time someone called it just to get the siz…

Branch prediction should be a super-dumb algorithm, but then Spectre comes along and, oh dear. Malware protection algorithms make fools of us all.

There's nothing about the bug that had anything to do with malware protection, or branch prediction, so I'm not sure how that statement applies to the conversation.

The bug was in ETW, which just happened to surface in a windows utility that ostensibly protects you from malware.

Re: Microsoft fixes 5-year-old Defender bug, reducing Firefox-related CPU use by 75%

#340

Post by schemescape »

sdfghswe wrote: post #100
arnaudsm wrote: post #40

Quick napkin math of the wasted power : Firefox has ~300e6 users, let's assume the bug wasted 5 extra watts 4 hours a day. That's 250 megawatts saved, the equivalent of an average coal power plant. Because some Microsoft engineer missed a bug.

> let's assume the bug wasted 5 extra watts 4 hours a day. How did you come to this?

Yes, the trace comparison in the link (which the author says is for browsing YouTube in Firefox) shows average CPU usage is down from roughly 5% to roughly 4%. That’s a great improvement, but I’d like to know why we should assume that translates to 5 Watts.
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