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Some odd behaviour ... when sending / uploading files, my CPU usage goes to about 100%; Activity Monitor reports 'Kernel Task' as the culprit. I first noticed this when sending emails in Mail, but it is also happening whenever I use any upload protocol:
- Email attachment;
- FTP using Cyberduck or FireFTP (within Firefox);
- Syncing Evernote (suspect this is also FTP?);
- FTP via command line (
ftp -u
)
Any idea why this happens, or how to stop it?
(OSX Lion 10.7.2, Macbook Pro 2.4 Core Duo; customisations include Growl and Quicksilver)
Update: first line of output from top -o cpu
:
PID COMMAND %CPU TIME #TH #WQ #PORT #MREG
0 kernel_task 122.3 20:13.81 73/4 0 2 1907
Update 2: Just decided to try this out using wifi instead of my USB 3G modem ... and the problem disappears! Five samples during ftp upload give:
$ top -l 5 -stats pid,command,cpu,th | grep kernel_task
0 kernel_task 0.0 71/2
0 kernel_task 2.2 71/3
0 kernel_task 2.1 71/2
0 kernel_task 2.1 71/2
0 kernel_task 2.2 71/2
So the issue seems to be any upload with the USB modem ... but would still be good to find a solution!
Do you have an antivirus running ? – Shadok – 2012-01-18T16:23:26.047
@Shadok ... no antivirus! Also tried this after quitting Quicksilver (thinking catalog updates might be happening during uploads), no effect. – Simbamangu – 2012-01-18T16:26:55.740
Ok, could you try opening a terminal and running 'top' before provoking the problem and pasting the display of the top command when the cpu is bound ? We'll see what's eating the CPU, it should help targeting the problem. – Shadok – 2012-01-18T16:40:28.810
Hmm... it might related to I/O because I have hard time believing the ftp command would consume such amount of kernel time. Just out of curiosity what is your max bandwith during ftp transfers ? – Shadok – 2012-01-18T17:20:28.200
Bandwidth goes up to 400 kilobit (USB modem) max, typically half that. Just checked with Mail attachment again (SMTP) and it's the same kernel_task process! – Simbamangu – 2012-01-18T17:25:08.593