Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower

[phoronix]

Phoronix: Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower

After running a lot of tests and then bisecting the Linux 4.20 kernel merge window, the reason for the significant slowdowns in the Linux 4.20 kernel for many real-world workloads is now known...

http://www.phoronix.com/vr.php?view=27092

[tildearrow]

Good it wasn't a kernel regression but a mitigation that can be disabled for performance.

[yoshi314]

how many more speedhacks there are in intel cpus that sacrifice security? it just never ends.

[Candy]

Hardware is cheap these days. Buy new and faster hardware. More RAM and a faster SSD.

... just wanted to use the same arguments that people throw at my head, when it comes to horrible GNOME performance.

[TemplarGR]

With all security mitigations enabled Skylake has lower IPC than Bulldozer... And they called Bulldozer a "failure". Sure, when you don't care about security at all you can get better IPC... How come AMD didn't think of this?

[shmerl]

Hardware is cheap these days. Buy new and faster hardware.

Like upcoming Zen 2?

[AsuMagic]

Hardware is cheap these days. Buy new and faster hardware. More RAM and a faster SSD.

... just wanted to use the same arguments that people throw at my head, when it comes to horrible GNOME performance.

Is there a Godwin point variant for DE holy wars?

[perpetually high]

Wow! That was quick, great work Michael thanks. Yesterday I finally remembered to turn off ad-blocker and have been doing my part to make sure you get paid for the time I spend frequenting here.

I'm so glad I turned all that shit off in GRUB, and stopped Intel from feeding me new microcodes on my Haswell.

$ dmesg | grep 'microcode'
[    0.000000] microcode: microcode updated early to revision 0x22, date = 2017-01-27
[    0.495848] microcode: sig=0x306c3, pf=0x2, revision=0x22
[    0.495866] microcode: Microcode Update Driver: v2.2.

$ sudo apt-mark showhold
intel-microcode
iucode-tool

$ grep 'GRUB_CMDLINE_LINUX_DEFAULT' /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet pti=off spectre_v2=off l1tf=off nospec_store_bypass_disable no_stf_barrier"

Friends don't let friends use Spectre mitigations on their desktop/notebooks.

[Zan Lynx]

I wonder if Hyperthreading is still worth it? Would it be interesting to run a speed test with it disabled?

[rhysk]

I wonder if Hyperthreading is still worth it? Would it be interesting to run a speed test with it disabled?

Intel may have already answered that question internally. Remember the recent chip marketing that only mentioned number of cores, no mention of threads or HT....