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How Do Spectre/Meltdown Fixes Affect The Linux Kernel? (phoronix.com)
"Using the newly minted Linux 4.19 feature code, fresh benchmarks were carried out looking at the performance cost of Spectre/Meltdown/Foreshadow mitigations on Intel Xeon v. AMD EPYC CPUs," writes an anonymous Slashdot reader:
Workloads affected by these CPU vulnerabilities mainly deal with I/O and frequent kernel calls while CPU bound tests are still found to be minimally impacted. When toggling these mitigations on Linux 4.19, Intel Xeon CPUs were found to be 10~15% slower with the default kernel while AMD EPYC CPUs dropped to about 5% slower.
It is not a slowdown, it is removing an undue [broken/illegal/dangerous] speedup ;-)
You can, of course, disable the mitigation. Just don't do it on anything processing external network packets, etc.
The only problem with AMD processors is they don't implement transactional memory operations. When they do, I will switch.
I have not noticed any slowdowns myself. I have seen examples of obvious slow down's in testing. But they probably are not significant enough to be noticed by a user. I know people who have opted not to install firmware and even some who have opted out of OS updates. I guess you take your chances and hope for the best or play it safe and maybe have a bit slower PC. For myself, I don't really have any tasks that has ever required every bit of performance. So for myself a 10 to 15% reduction is not a big deal.
I use os/2 you insensitive clod.
The short of the current consensus is that everything about Intel's x86 now sucks, forever. Pointer-chasing has become expensive to the detriment of vast swathes of system code, and just about all of application code. System calls now cost the same as they would in 32-bit 4G/4G setups, i.e. as much as a context switch but also some trampoline overhead.
And don't get me fucking started on Spectre. You need a crack team of leethaxxers born for the job to even begin to test whether a given binary is vulnerable to a given sequence of Spectre gadgets and their primary invocation pathway (i.e. ROP or some such). There aren't enough of those to support compiler tuneups across the industry (starting from even GCC!), so the current magic bullets come at a steep cost and are gonna be broken for about a decade still.
Guess they should've given some thought to security back when they were taping out the Pentium Pro, eh.
if (cpu == intel) { // this is why benchmarking is prohibited -- don't tell anyone
if (microcode_version != current) {
crash_cpu();
} else {
}
disable_l1_cache();
disable_l2_cache();
disable_l3_cache();
disable_isntr_cache();
disable_data_cache();
disable_tlb_cache();
if {ultra_secure_mode == 1 && num_cores > 1 && customer_has_paid_us_money(lookup_microcode) );
for (i=1;i=core_count;i++) {
disable_core(i);
disable_smm_mode();
disable_secret_cpu_used_for_management_engine();
disable_management_engine();
}
}
it's "only" a 15% performance penalty, just those little caches are disabled, nothing to worry about, except if you go to "ultra_secure" mode, than the performance penalty jumps.
Where's the BeOS port you promised us in 1997?
Il n'y a pas de Planet B.
I believe I am in love with Hosts files. I feel a bit of.. a bit of pee coming up, oh yes. A small amount, a droplet, of pee is now running down my legs. This is so invigorating! Bring me back to life, Hostfile engine! Another droplet from the fountain of life, no, many droplet. Verily a stream of urine is now soaking my pants. This is an amazing day.
You're out of luck. However, AFAIK, a Haiku port is upcoming.
Don't you have anything better to do than IMPERSONATE me?
APK
P.S.=> Seriously... apk
I am APK the great "LORD of HOSTS", a.k.a. AlecStaar from ArsTechnica or Alexander Peter Kowalski.
See subject & APK Hosts File Engine 2.0++ 64-bit for Linux h t t p : / / I . a m . a . f u c k i n g / a s s h o l e . r e t a r d . z i p (remove spaces between characters & download).
I am the godlike creator of various GUI front-ends for other people's configuration files.
When presented with facts I rebut them with wild speculations, false support, and out of context quotes
All of my accomplishments revolve around me being proven to be an annoying spamming asshole
See me be proud of my inability to be a functional adult
Bask in my debilitating mental illness
Hear me tell stories about me living large drinking miller lite in my ramshackle duplex with a roommate at age 54.
You must be conspiring with the Jews and Soros if you disagree with me
Mistaking mockery and parody for impersonation is how I think people flatter me because I can't possibly understand that they detest me.
Watch as I claim I am world class and a winner but in reality I am a fucking loser.
Witness my descent into madness
APK
Local exploits are a lot harder to pull off than remote exploits. The primary gatekeeper of the worlds IT device is Secure Shell. I just have one simple question: If this shit is so catastrophic and bad like we've been hearing, then where the fuck are the OpenSSH remote root exploits? Bullshit flag thrown. Now point me to the exploit code that returns a root prompt and I'll drink your security Chicken Little kool-aid. Until then *yawn*.