Toots for tomasv@fosstodon.org account

Written by Tomas Vondra on 2025-01-20 at 12:01

A couple weeks ago I upgraded one my home lab machines I use for benchmarking. Aside from getting a new Ryzen, the main change was getting a bunch of Samsung 990 PRO M.2 SSDs for storage. And the performance I'm seeing is rather atrocious :-(

For most workloads (reads/writes, sequential/random) it works fine, e.g. for random writes I can get ~50k IOPS (iodepth=1) quite easily. But as soon as I ask fio to do fsyncs (fsync=1), the performance just absolutely tanks to ~200 IOPS.

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Written by Tomas Vondra on 2025-01-20 at 12:01

Of course, fsync=1 is expected to have some impact. Every SSD I own shows the same effect, but never this bad. For example:

WD Ultrastar SN640: 50k => 40k IOPS

Intel DC S3700 (6x RAIO0): 24k => 6k IOPS

So the drop 50k => 200 IOPS seems terrible. What am I doing wrong? Any suggestions for a better option (device/model) - still affordable, but handling fsync reasonably?

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Written by Tomas Vondra on 2025-01-03 at 18:02

[#]Prague

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Written by Tomas Vondra on 2024-11-07 at 15:25

OK, I'm not the youngest person anymore, but I sure hope I'm not at the senile stage yet ... #LinkedIn

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Written by Tomas Vondra on 2024-11-05 at 10:48

My day so far:

• decide to investigate an annoying rare bug

• write a ugly script to stress test the issue

• hit three separate bugs in that code

🤦‍♂️

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Written by Tomas Vondra on 2024-10-30 at 12:43

Got a really cool 3D-printed elephant at the #postgres meetup yesterday.

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Written by Tomas Vondra on 2024-10-01 at 15:31

My afternoon:

• Tweak the IPMI config of a test machine running in the other room.
• Terrible beeping noise starts. Something is clearly wrong, making BIOS very unhappy!
• Frantically search which IPMI sensor is causing the alerts.
• Realize there's a truck backing outside the window.

😅

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Written by Tomas Vondra on 2024-09-25 at 10:09

First world problem: I ended up just upgrading the CPU to the most powerful one available (for that socket), but now the UPS is beeping angrily that the machine draws too much power when under load 😥

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Written by Tomas Vondra on 2024-09-14 at 10:31

Asking for advice:

If you wanted to buy a mid-range machine for a home lab, to be used primarily for benchmarking, which CPU would you pick?

~99% of users are on x86-64, but Intel or AMD? I was going with Intel in the past, but I'm afraid the big.LITTLE just adds unpredictable noise, making benchmarking harder. But I also heard the perf counters on AMD are not as precise, which is not great.

Opinions?

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Written by Tomas Vondra on 2024-09-01 at 17:01

Anyone using Thinkpad P1 G7 with Linux?

What's the experience? Anything not working correctly (e.g. suspend), fan noise, and so on?

I'm thinking about getting the model with Core 165H and integrated GPU. Have been quite happy with Dell Precision over the past decade, but they seem to only do them with discrete GPUs now ☹️

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