On 10:35 Thu 15 Nov , Lee Jones wrote: > On Thu, 15 Nov 2012, Jean-Christophe PLAGNIOL-VILLARD wrote: > > > On 10:04 Thu 15 Nov , Lee Jones wrote: > > > This patchset supplies a new tool which measures boottime inclusive > > > of bootloader involvement. It seems to be accurate and adds no > > > latency to the booting of the system. > > > > > > In the first round of testing we booted the kernel 3 times each with > > > boottime enabled and disabled. Actually, when it was disabled, the > > > code was completely removed from the kernel source and the kernel was > > > rebuilt. The difference between present & enabled and completely > > > removed was very little indeed. In fact, averaging out the 3 runs of > > > each, when boottime was enabled the system booted 4ms _faster_, go > > > figure! > > > > > > Enabled Disabled > > > 1st run 2.983093 2.985168 > > > 2nd run 2.973266 2.971801 > > > 3rd run 2.975402 2.987304 > > > Average 2.977254 2.981424 -0.004171 (-4ms) > > > > > > > > > For the next round of testing, we delayed the bootloader for varying > > > amounts of time, then started to remove key components from kernel > > > functionality to see if the boottime system would pick-up on them. > > > > > > /* Hang around in the bootloader for a while. */ > > > $ cat /sys/kernel/debug/boottime/summary > > > kernel: 42864 msecs > > > total: 42864 msecs > > > kernel: cpu0 system: 56% idle: 43% iowait: 0% irq: 0% > > > cpu1 system: 4% idle: 95% iowait: 0% irq: 0% > > > > > > /* Hang around in the bootloader for a smaller amount of time. */ > > > kernel: 12351 msecs > > > total: 12351 msecs > > > kernel: cpu0 system: 56% idle: 43% iowait: 0% irq: 0% > > > cpu1 system: 2% idle: 97% iowait: 0% irq: 0% > > > > > > /* Instant boot. (1st run) */ > > > kernel: 7833 msecs > > > total: 7833 msecs > > > kernel: cpu0 system: 55% idle: 44% iowait: 0% irq: 0% > > > cpu1 system: 3% idle: 96% iowait: 0% irq: 0% > > > > > > /* Instant boot. (2nd run) */ > > > kernel: 7817 msecs > > > total: 7817 msecs > > > kernel: cpu0 system: 53% idle: 46% iowait: 0% irq: 0% > > > cpu1 system: 8% idle: 91% iowait: 0% irq: 0% > > > > > > /* Instant boot. (3rd run) */ > > > kernel: 7747 msecs > > > total: 7747 msecs > > > kernel: cpu0 system: 56% idle: 42% iowait: 0% irq: 0% > > > cpu1 system: 2% idle: 97% iowait: 0% irq: 0% > > 7/8s? on a u9500 wow it's really slow > > No, this is a u8500. > > > I do 2/3s here > > Really? You installed this quick. > > Are you sure you did it correctly? yes we spend less than 2s (~ 1.5s) in the bootloader
I measure it via scope > > Don't forget, this times from power-on to userspace. yes to the shell prompt and gexbox 13s IIRC application Best Regards, J. > > -- > Lee Jones > Linaro ST-Ericsson Landing Team Lead > Linaro.org │ Open source software for ARM SoCs > Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
