Intel-based Macs: Inexplicable high processor loads when Windows Sharing is turned on (#2): Possible fix

We continue to report on an issue where processor load spikes to inordinate levels when the "Windows Sharing" function is turned on in the Sharing pane of System Preferences.

The problem is inconsistent, with some users reporting that simply turning Windows Sharing off then back on alleviates the high processor loads.

One reader writes:

"I used Windows File Sharing with Parallels on the same machine to be able to connect to the Mac side from Windows when I was having trouble with Parallel's shared folders. It worked fine, but a couple of days later, I noticed the exact symptoms your article describes, and the cause was the same: Windows File Sharing. The problem persisted after reboots and with or without Parallels running. Since I now had Parallels shared folders working, I just turned off Windows File Sharing, and everything was fine. A few days later, I turned it back on again, just to test it, and it no longer produces that problem. I'm not sure what (if anything) changed in that time. I first noticed the problem last Saturday the 3rd, so there weren't any Apple software updates that might have fixed it.'

Another reader, Stephane, writes:

"I have the exact same problem, with my CPU steadily climbing to 40% usage by user and neither top or monitor shows the threads using the CPU. Turning off the Windows Sharing solved my problem instantly. "

And another reader adds:

"I have also experienced this issue. Just tonight when I was transferring my files between my PC and MacBook (White 1.83GHz, 1GB RAM, 100GB HD), I noticed my processor was staying at around 50% on both cores and fan was constantly on. I went into System Preferences > Sharing and turned off Windows File Sharing and immediately the processor usage went down to almost nothing, about 5-10%. Toggling Windows File Sharing back on did not bring the problem back.'

Fix Aside from toggling Windows Sharing off and on (in some cases, several attempts are required), this issue can generally be resolved by entering the following command in the Terminal (located in Applications/Utilities)

• sudo rm -r /var/log/samba/log.nmbd

This command will delete the Samba (SMB) log, which appears to swell when Windows Sharing is turned on for some Intel-based Macs. You may need to re-enter this command when you see processor usage spiking again.

Feedback? Late-breakers@macfixit.com.

Previous coverage:

• Intel-based Macs: Inexplicable high processor loads when Windows Sharing is turned on

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