100% CPU just transferring files?

[altano (Alan)]

Hello,

I have an underpowered CPU (Intel Pentium processor D1508) but I still wouldn’t expect Syncthing to saturate the CPU while transferring files (it is not scanning).

I took some cpu profiles: would anyone have the time to take a peek and tell me what might be the issue here?

syncthing-cpu-linux-amd64-v1.23.2-122555.pprof (16.4 KB)

syncthing-cpu-linux-amd64-v1.23.2-122513.pprof (17.5 KB)

[calmh (Jakob Borg)]

Well, something is going to be the limit – if it’s not the network or the I/O it’s going to be the CPU. If that CPU doesn’t offer whatever extensions are used for hardware crypto & hashing then that’s likely to be the bottleneck.

Profile boils down to … crypto, and hashing:

[altano (Alan)]

Thank you for taking a look. This is a 2-core 4-thread CPU with support for AES-NI. I have no idea what else to check wrt crypto/hasing support but here is the Intel Ark page: Intel Pentium Processor D1508 3M Cache 2.20 GHz Product Specifications

[altano (Alan)]

Also, I should note that it’s not just using 100% CPU but also bottlenecked to 30MB/s transfer speeds (this is a 10gbe pipe)

[AudriusButkevicius]

AES-NI is not very useful for SHA256.

2 core 4 threads is less than what most people carry in their pockets nowadays, and phones, while still being considered “weak” devices, usually ship SHA extensions on newer CPUs.

I suspect the transfer rate will be simillar to the hashing rate reported on startup.

[altano (Alan)]

I didn’t realize htop hid kernel processes by default. It looks like I am hitting a performance bottleneck with my CPU but it’s not coming from Syncthing’s hashing: it’s my zfs pools encryption. This CPU is so freaking old it can’t handle writing to an encrypted filesystem. heh.

I guess an upgrade is in order.

Thanks @AudriusButkevicius and @calmh!

[Arneko]

…this support request thread should be entered in the fame hall of support request threads…

• providing all the necessary info in the first post
• getting a diagram detailing what is happening by the devs
• realizing the issue is something entirely different (albeit with no help from the forum)

Pure gold.

My compliments to both OP and the devs.

[ProactiveServices (Adam Piggott)]

@altano

This CPU is so freaking old it can’t handle writing to an encrypted filesystem. heh.

It’ll help keep you warm if you run it under your desk, though

[bikerchris (Chris)]

Just a small addition, I run ST on a TrueNAS Core install running on an Intel G4560 build (2C/4T)/16GB ECC RAM. It works perfectly well and rarely uses 100% - I confess I don’t encrypt files though.