Re: [BUG] perf tests: Test converting perf time to TSC

From: Peter Zijlstra
Date: Thu Oct 03 2013 - 09:58:12 EST


On Thu, Oct 03, 2013 at 02:49:09PM +0300, Adrian Hunter wrote:
> You can boot with notsc and perf still seems to work
> e.g.
>
> $ dmesg | grep -i tsc
> [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-3.11.0+ root=UUID=f1b4c71a-15aa-41a6-8898-cdde49966bce ro ignore_loglevel earlyprintk=ttyS0 console=ttyS0,115200n8 no_console_suspend notsc=1
> [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.11.0+ root=UUID=f1b4c71a-15aa-41a6-8898-cdde49966bce ro ignore_loglevel earlyprintk=ttyS0 console=ttyS0,115200n8 no_console_suspend notsc=1
> [ 0.000000] tsc: Kernel compiled with CONFIG_X86_TSC, cannot disable TSC completely
> [ 0.000000] tsc: Fast TSC calibration using PIT
> [ 0.004000] tsc: Detected 2593.932 MHz processor
> [ 0.224000] TSC deadline timer enabled

Yeah, and we still use the TSC deadline timer too.. I think we should
seriously consider removing the notsc option. I really don't know what
its good for.

Thomas, Ingo, hpa?
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