JATth

Python is just a pile of dicts/hashtables under the hood. Even the basic int type is actually a dict of method names:

x = 1
print(dir(x))
['__abs__', '__add__', '__and__', '__bool__', '__ceil__', '__class__', '__delattr__', '__dir__', ... ]

PS: I will never get away from the fact that user-space memory addresses are also basically keys into the page table, so it is hashtables all the way down - you cannot escape them.

I know two friends… who would absolutely lynch you for doing this.

Anyway, it has been fun following them and occasionally ask “whats this card worth?” and general answer has been 5-50€ a card. The cards can be worth more than literal money.

I never finished reading my CMake book that weights about two kilos. It’s now outdated, except for the core concepts.

H̢̱̀e͖ͧ͘r͈̔́e̖̅̀ͅ ḩ͒͏̩̲ẹ̽ͯ̀ c̔͑͠҉̬o̢̢̠̜̓̚m̷̻̳ͧͪ͘ę̢̥̋̀s̢͈̲ͧ̀͜ͅ,̧̔͞ͅ f͖͗̿̕͝ȅ̴̶̩̂͟a̸̡̯͈̼͋͡s̗̋̀̀̀̀͟t̒̾͏̯ y̸̛̟̽̇o̢̟̜͂͆ͯ͘͜u̧̧̜͔͇ͭͫ́̚͞r̀̃͑̓͒͏̮ e̍̒̇ͯ҉̴̲̭y̷̰̖ͨ̑͜e̓ͭͭ͂̕҉̸̛̦̱̤̫͢s̡̛̫͋̕ o̢͉̘͚̤̅ͫͤ̓ͭ̕͡n͊͘҉̲̟̖͔͝͞ t̷̟͊̽h̨̦͎̅̄ͪ́̚͘͠i̶̢̛̬̞̦͊̅̏̀́s̶̸̢̹̹͕̩̜̣̎ͫͤ͐̈̀.̛̰̼̗̺̼͗ͣ̏́̚͟͠.̵̪ͥ̈̚̚͞ͅ.̷̶͎̞̳̘̈͋ͬ̈͂͒͠ z̸̛̫̓͜͟͡ḁ̧ͨ͊͗ͫͫ̅́͢͠͠l̵̴͒͏͚̥̻g̩͎̲̼̠̿̅ͩ͌̇͟o̢̝͍͔͍̼̼ͤͦ̎́͘͝ i̷ͧ̅̂͟͡͠͞҉̸̙̱͍͈̝̠̺̀ͅs̗̮͇̪̯̋͋́̕ t̵̶̛̰̘̰̫̬͖̜͗̒͗̉̿͌̀̀͢ẖ̴̴̡̭̪̉̌̈́͗͘e̵ͬ̃ͬ͌͆̍͏̧̡̧̦̘͇͕͙̳̹͜ ạ̳̺͎̤̺̖̠̔̈ͮ̉̌̓̀́͟͢͞͞n̊͏̰̖̘̖̭̰̖̕͢ş̴̽͘҉̮̞̼̱w̨̢̠̻͐̐͑̊͢͞e̢̡̛͖̙̟̣͋͆͘̕ͅŗ̧̯ͪ͘͘͜͡.̭̘͇͓̹̻̖̖͉͊ͪ́

Bookmarking doesn’t work for me, too limited, and starts a horrible trend of duplicating them. So they are useless for tab history managment. Also, the linear tab history is not very useful… same problem, the entries get duped eventually. I often don’t want to restore the tabs from the last day whatever, but restore an specific set of tabs. Some times even multiple sets, and switch between these.

I really would like an Firefox feature, where the tabs would be part of a “tab history tree”. Opening a link in a tab would add it as a “sub-tab” of the parent tab. In history.

So when a doing a search or refining one many times, this would end-up linking all the opened tabs to the originating tab. A new tree of tabs could be started by just opening an empty tab, and a “tab organizer UI” should allow to move/group that into an existing tab tree if needed. (The tab-bar UI doesn’t need to visualize the tree-of-tabs. The tabs would be just auto-organized this way in the history)

I think this would allow to clear all of the currently open tabs in any window, but the tabs could still be neatly restored from the history on per-tree basis in any window. Restoring a tab-tree would allow to continue making refinements to it, or clone it. Currently multi-window tab restoring in FF is kinda borked, and only the last window’s open tabs are restored automatically.

/end-of-wordsoup-for-today.

nohz_full confusingly also helps with power usage… if the cpu doesn’t have anything to run, no point waking it up with a scheduler-tick IPI… but also no point trying to run the scheduler if a core is peaking with a single task… With nohz the kernel overheard basically ceases to exist for a task while the it is running. (Thought the overhead just moves to non-nohz cpu cores)

To be fair, there should be some heuristics to boost priority of anything that has received input from the hardware. (a button click e.g.) The no-care-latency jobs can be delayed indefinitely.

Why can Windows do it when Linux can’t?

Windows lies to you. The only way they don’t get this problem is that they are reserving some CPU bandwidth for the UI beforehand. Which explains the 1-2% y-cruncher worse results on windows.

I agree that UI should always take priority. I shouldn’t have to do anything to guarantee this.

I have HZ_1000, tickless kernel with nohz_full set up. This all has a throughput/bandwidth cost (about 2%) in exchange for better responsiveness by default.

But this is not enough, because the short burst UI tasks need near-zero wake-up latency… By the time the task scheduler has done its re-balancing the UI task is already sleeping/halted again, and this cycle repeats. So the nice/priorities don’t work very well for UI tasks. Only way a UI task can run immediately is if it can preempt something or if the system has a somewhat idle CPU to put it on.

The kernel doesn’t know any better which tasks are like this. The on-going EEVDF, sched_ext scheduler projects attempt to improve the situation. (EEVDF should allow specifying the desired latency, while sched_ext will likely allow tuning the latency automatically)

No, I definitely want it to use as many resources it can get.

taskset -c 0 nice -n+5 bash -c 'while :; do :; done' &
taskset -c 0 nice -n+0 bash -c 'while :; do :; done'

Observe the cpu usage of nice +5 job: it’s ~1/10 of the nice +0 job. End one of the tasks and the remaining jumps back to 100%.

Nice’ing doesn’t limit the max allowed cpu bandwidth of a task; it only matters when there is contention for that bandwidth, like running two tasks on the same CPU thread. To me, this sounds exactly what you want: run at full tilt when there is no contention.

“The kernel runs out of time to solve the NP-complete scheduling problem in time.”

More responsiveness requires more context-switching, which then subtracts from the available total CPU bandwidth. There is a point where the task scheduler and CPUs get so overloaded that a non-RT kernel can no longer guarantee timed events.

So, web browsing is basically poison for the task scheduler under high load. Unless you reserve some CPU bandwidth (with cgroups, etc.) beforehand for the foreground task.

Since SMT threads also aren’t real cores (about ~0.4 - 0.7 of an actual core), putting 16 tasks on a 16/8 machine is only going to slow down the execution of all other tasks on the shared cores. I usually leave one CPU thread for “housekeeping” if I need to do something else. If I don’t, some random task is going to be very pleased by not having to share a core. That “spare” CPU thread will be running literally everything else, so it may get saturated by the kernel tasks alone.

nice +5 is more of a suggestion to “please run this task with a worse latency on a contended CPU.”.

(I think I should benchmark make -j15 vs. make -j16 to see what the difference is)

It tastes like banana? I’m in, I have been looking for bourbon that actually tastes like banana/pineaple…

I once helped a person with their computer. They complained the they cant save the their photos. Well, their onedrive was filled to brim with crap, while the local 1Tb disk was empty because they had zero idea how storage and folders work. I had to explain her there is literally 1000x more fast disk space available, so please dont save into onedrive.

I’m actually bit sad that I had to move onto a ISP which has zero IPv6 support, as I previously did have IPv6. The last thing I did on that connection was to debug the hell out of my IPv6 code I had developed.