Opened 15 years ago

Closed 15 years ago

Last modified 10 years ago

#4734 closed Bug report (wontfix)

High CPU usage while downloading using explicit TLS

Reported by: PhiWi Owned by:
Priority: high Component: FileZilla Client
Keywords: CPU, Mac, TLS Cc: p.winkler@…
Component version: Operating system type: OS X
Operating system version: 10.5.8


On my 2.8GHz Core 2 Duo iMac I get around 70% CPU usage while downloading files with filezilla from a host using explicit TLS. I am not downloading at very high speed, its a home line (3MB/s max.)

When I am just browing on the server there is no significant CPU usage.

Probably some issue regarding OpenSSL?

Attachments (2)

Bild 16.png (134.6 KB ) - added by PhiWi 15 years ago.
screenshot_windows.png (60.9 KB ) - added by PhiWi 15 years ago.

Download all attachments as: .zip

Change History (6)

by PhiWi, 15 years ago

Attachment: Bild 16.png added

comment:1 by Tim Kosse, 15 years ago

Status: newmoreinfo

FileZilla uses GnuTLS, not OpenSSL.

Increased CPU usage during TLS encrypted transfers is to be expected compared to plain regular FTP. The encryption can add quite some overhead.

What is the cipher you are using? It gets displayed if you click the certificate icon in the statusbar.

comment:2 by PhiWi, 15 years ago

Cc: p.winkler@… added
Status: moreinfonew

cipher is AES-256-CBC

when downloading using FizeZilla for Windows the CPU load is low / moderate.
I tested using Windows 7 on a 2.4GHz Core 2 Duo notebook.
(see screenshot_windows.png)

by PhiWi, 15 years ago

Attachment: screenshot_windows.png added

comment:3 by Tim Kosse, 15 years ago

Resolution: wontfix
Status: newclosed

I did some profiling, there is nothing I can do to decrease CPU usage. Most of the CPU usage is spent inside libgcrypt over which I have no influence.

comment:4 by PhiWi, 15 years ago

ok, thanks alot for yor effort!

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