@ljs @vbabka This tooling has been around for over a decade. During the month of December, I figure I can run it on my server and workstation as this month is usually slower than other months. But I recently upgraded my server (28 cores / 56 hyperthreaded) and since the profiling updates a single integer (no locking, I’m looking for estimates not real numbers) but the cache line contention is making it impact this server much harder than my older server. It has actually slowed this down much more. I’m thinking of just running it for one week and not three like I use to.

Anyway, the likely/unlikely can be a big performance increase. I sped up the ftrace ring buffer by around 50% by placing strategic likely and unlikely around.

My fiix: https://lore.kernel.org/all/20231201145936.5ddfdb50@gandalf.local.home/

And it looks to have found a bug right off the bat!

It’s the month of December. Do you know what that means? It means it’s time to run my workstation and server with branch tracing enabled! https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/compiler.h#n50

[$] Deferred scheduling for user-space critical sections https://lwn.net/Articles/948870/ #LWN

Even though, I disabled suspend, I still get these broadcast notices! 😆

Broadcast message from gdm@bxtest on tty1 (Thu 2023-10-26 00:01:04 EDT):

The system will suspend now!

But nothing happens, as suspend is now a nop.

@0leil Well, this is a test machine that’s not a server. When I first set it up, it acted as a desktop. Then its now just another box I test on.

OK, I just upgraded my baremetal machine from Fedora 33 to Fedora 38 (by stepping through 35 and 37 as in between steps). I haven’t used this machine in a long time as I now do most of my testing with VMs. But I’m doing some performance testing that I wanted to know baremetal numbers.

WTF Fedora! 38 introduced a “suspend in 15 minutes if not logged in”. It doesn’t care if you are ssh’ed in or not! What’s worse is that this machine isn’t even hooked to a monitor (serial console only).

Luckily, I found a link that shows me how to disable that. 😛

@vbabka and forget about it? No, this is usually a “Oh crap I need to finish this now” situation.

Don’t you hate it when you go into one of your git repos to do some updates, and realized you have a large diff of uncommitted code of a work in progress that you left and forgot about! 😛

@llvm That’s why I added “pass-away” as that’s what I plan on doing for my retirement 🤪

@hergertme Sorry, I left screaming….

@mansr And the authors of that code will forever have their legacy in the code base!

I just realized. The more you comment your code and make it understandable, the easier it is for other people to takeover and rewrite your code. This means that when you retire/pass-away, your code will likely be quickly overwritten and your legacy gone from the active code base.

So, if you write complex clever code with little to no documentation, your code is more likely to be immortalized in the code base as everyone will be too afraid to touch it and possibly break it.

I thought of this when looking into the Linux TTY code base

@iw That slide is much more interesting in the presentation because it now has baby tux angrily sitting on that chair!

I wasn't a speaker at Embedded Recipes this year but I still pulled off my obligatory selfie with the ER speakers.

Traditional mandates all ftrace talks must start with a selfie from a camera and not a phone! At #kr2023

@KernelRecipes

I think the demonstration was to show that the audience would do anything for Paul.

Paul McKenney using toilet paper to describe latency of CPUs

My obligatory selfie at Kernel Recipes