[arch-general] Extremely slow battery status on MBP

[Panayiotis Tembriotis]

On Fri, Aug 28, 2015 at 11:40:15AM -0700, Emanuel Evans wrote:
> Apologies for the repeat posting--I think my previous posting ended up
> bouncing due to some misconfigured dmarc settings. Anyways, I have kind
> of a weird issue that I'm having trouble debugging. On my MacBook Pro
> (11,1), checking battery status (through acpi or the /sys filesystem)
> becomes extremely slow after the computer's been on for a while. Here's
> an example:
> 
> $ time cat /sys/class/power_supply/BAT0/status
> Charging
> 
> real	0m54.519s
> user	0m0.000s
> sys	0m4.663s
> 
> dmesg and journalctl aren't outputting anything during the call, and I
> tried strace during the command and there was no output during the
> blocked time. It's highly intermittent--acpi can take anywhere from 0-60
> seconds with no discernible pattern, except that it doesn't happen when
> the battery is plugged in and charged. Any ideas for how to debug this
> further, or possible solutions? Thanks so much!

I'm experiencing the same issue on my MacBook Pro (10,2). AFAIK it is
caused by the sbs kernel module so you might be better off asking on the
kernel mailing list. There is also a relevant bug report [1].

[1] https://bugzilla.kernel.org/show_bug.cgi?id=94651