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Linux kernel maintainer. Compilers and virtualization at Parity Technologies.

Jarkko Sakkinen

My pro tip for Amazon: if successful meetings are so important why not just require people to show up to those F2F?

I think staff would be more motivated with that constraint than enforced in-office weeks 🤷

#amazon #remote #work
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Wow! Fedora Linux 41 beta today, _and_ twelve years at Red Hat for me!

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Jarkko Sakkinen

Edited 3 months ago
After having MacBook Pro for 1.5 years from Tampere University picking the dev laptop for the new job was a no brainer options to pick being Macbook Pro or x86 Linux laptop.

MacOS is pure garbage a development environment. If you get one there is no other ways to make usable except installing Asahi Linux. Working with toolchains sucks, virtualization sucks and conceptually containers do not in reality exist.

I'm not even joking when I say that if i had picked Macbook Pro as my dev laptop for the new job it would statistically show in the performance reports over period of time as a negative impact. It just is super bad operating system for writing code.

I still love my personal Mac mini which is over-expensive audio plugin host :-) It does deliver in that task tho and works well also for watching Netflix.

Phew, it was nice to let all the hate for Macbook Pro out ;-) Piece of shit laptop tbh.
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Jarkko Sakkinen

I was looking for something that would be a bit like Maple and Matlab for working as calculator, plotting and stuff like that but not as involved as those tools. After trying bunch of options I realized https://julialang.org/ is pretty much size-fit of this niche.
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Jarkko Sakkinen

I like eBPF because it allows me to set conditions and measurement points so freely. A performance issue that took me some years ago two days to uncover takes now few hours. Improving tools brings so much more productivity than ChatGPT ever could.
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Jarkko Sakkinen

I think I move my PR for v6.12 to late this week given that the getting performance improvements for TPM encryption are a priority to fix. Would not make sense to postpone them to v6.13 in my opinion.
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Jarkko Sakkinen

First performance fixes for TPM HMAC encryption:

https://lore.kernel.org/linux-integrity/D4727YOJY8KZ.L6RKMRBKRCSN@kernel.org/T/#m22ed621c65c75c75900fe77c6b963ac98eb1b624

I don't expect this to fully address the performance challenges. It is the first axis here. Other axis is the session creation but these are independent issues.
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Jarkko Sakkinen

one of my favorite game themes: https://www.youtube.com/watch?v=ICX6hK3Se6k
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Jarkko Sakkinen

Two weeks after this left at Tampere University working in https://sochub.fi/. Not that much is going to change to because I'm still happily stuck at my home and working on RISC-V peculiarities. It's a broken CPU architecture still in my opinion but that's why also fun to work with :-)
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Ukrainaan kerätään läppäreitä, tablet-laitteita, puhelimia, latureita, jne. pelastuspalvelujen kautta.

https://intermin.fi/ukraina/materiaaliapu-ukrainaan/laptops-for-ukraine

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ahh yes, the little known 3M Sandblaster Pro

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Jarkko Sakkinen

I switched back to GNU screen from tmux :-) Color issues are gone in 5.0. I was using screen anyway all the time because it can do serial ports.
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Jarkko Sakkinen

Edited 3 months ago

Cool, GNU Screen 5.0 is out [1].

Screen has its set of perks when compared to tmux:

  1. screen -L -dmS <session name> <command> (I’m aware of tmux pipe-pane but it is not atomic with the session creation).
  2. screen <serial port>
  3. Local layout for a session per client.

When doing kernel CI the first bullet can be sometimes particularly useful.

[1] https://lwn.net/Articles/987700/

#screen #tmux #lwn

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Edited 3 months ago

OK, it's official. The next ER will be May 14-16 in Nice, France. -- https://embedded-recipes.org

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This is why women cover their drinks when enters the room.

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Jarkko Sakkinen

Edited 3 months ago

This was pretty cool:

❯ sudo bpftrace -e 'k:tpm_transmit { @start[tid] = nsecs; } kr:tpm_transmit { @[kstack, ustack, comm] = sum(nsecs - @start[tid]); delete(@start[tid]); } END { clear(@start); }'
Attaching 3 probes...
^C

@[
    tpm_transmit_cmd+46
    tpm2_flush_context+120
    tpm2_commit_space+197
    tpm_dev_transmit.constprop.0+137
    tpm_dev_async_work+102
    process_one_work+374
    worker_thread+614
    kthread+207
    ret_from_fork+49
    ret_from_fork_asm+26
, , kworker/4:2]: 2860677
@[
    tpm_dev_transmit.constprop.0+111
    tpm_dev_async_work+102
    process_one_work+374
    worker_thread+614
    kthread+207
    ret_from_fork+49
    ret_from_fork_asm+26
, , kworker/16:1]: 3890693
@[
    tpm_transmit_cmd+46
    tpm2_load_context+195
    tpm2_prepare_space+410
    tpm_dev_transmit.constprop.0+54
    tpm_dev_async_work+102
    process_one_work+374
    worker_thread+614
    kthread+207
    ret_from_fork+49
    ret_from_fork_asm+26
, , kworker/4:2]: 9058524
@[
    tpm_transmit_cmd+46
    tpm2_save_context+179
    tpm2_commit_space+314
    tpm_dev_transmit.constprop.0+137
    tpm_dev_async_work+102
    process_one_work+374
    worker_thread+614
    kthread+207
    ret_from_fork+49
    ret_from_fork_asm+26
, , kworker/4:2]: 11426260
@[
    tpm_transmit_cmd+46
    tpm2_load_context+195
    tpm2_prepare_space+318
    tpm_dev_transmit.constprop.0+54
    tpm_dev_async_work+102
    process_one_work+374
    worker_thread+614
    kthread+207
    ret_from_fork+49
    ret_from_fork_asm+26
, , kworker/4:2]: 14182972
@[
    tpm_transmit_cmd+46
    tpm2_save_context+179
    tpm2_commit_space+155
    tpm_dev_transmit.constprop.0+137
    tpm_dev_async_work+102
    process_one_work+374
    worker_thread+614
    kthread+207
    ret_from_fork+49
    ret_from_fork_asm+26
, , kworker/4:2]: 22597059
@[
    tpm_dev_transmit.constprop.0+111
    tpm_dev_async_work+102
    process_one_work+374
    worker_thread+614
    kthread+207
    ret_from_fork+49
    ret_from_fork_asm+26
, , kworker/4:2]: 1958500581

Gives me total ns time for each possible stack while bpftrace was running :-) Nothing spectacular but I believe this might be enough to get hold of a performance regression:

https://lore.kernel.org/linux-integrity/D43JXBFOOB2O.3U6ZQ7DASR1ZW@kernel.org/

I’m a total beginner with eBPF stuff, and not an expert in tracing and profiling, so any improvement suggestions are welcome.

#linux #kernel #bpftrace

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Thorsten Leemhuis (acct. 1/4)

Is there anything you would like to ask the Foundation's TAB (Technical Advisory Board)?

Then come to the "ask us anything" session with the current TAB at the @linuxplumbersconf 2024, which is currently scheduled for 9:00 on Friday, September 20[1].

And if you can't be there, just tell me your questions: I'll try to bring a few of them forward if I get a chance.

[1] https://lore.kernel.org/all/87zforv3zc.fsf@trenco.lwn.net/

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Jarkko Sakkinen

I needed to check if files went to a generated image and by accident noticed that 7z is actually quite nice ad-hoc tool for checking such thing:

❯ 7z l efi-part.vfat

7-Zip [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21
p7zip Version 16.02 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,64 bits,32 CPUs 13th Gen Intel(R) Core(TM) i9-13900KF (B0671),ASM,AES-NI)

Scanning the drive for archives:
1 file, 33521664 bytes (32 MiB)

Listing archive: efi-part.vfat

--
Path = efi-part.vfat
Type = FAT
Physical Size = 33521664
File System = FAT16
Cluster Size = 2048
Free Space = 19079168
Headers Size = 90112
Sector Size = 512
ID = 2421383688

   Date      Time    Attr         Size   Compressed  Name
------------------- ----- ------------ ------------  ------------------------
2024-09-10 20:59:32 D....                            EFI
2024-09-10 20:59:32 ....A     14349312     14350336  bzImage
2024-09-10 20:59:32 D....                            loader
2024-09-10 20:59:32 D....                            loader/entries
2024-09-10 20:59:32 ....A          126         2048  loader/entries/buildroot.conf
------------------- ----- ------------ ------------  ------------------------
2024-09-10 20:59:32           14349438     14352384  2 files, 3 folders
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