Hi Josh, Thank you for your review!
On 04/24/2014 04:55 PM, Josh Triplett wrote: > On Thu, Apr 24, 2014 at 02:07:33PM +0200, Michael Opdenacker wrote: >> This patch proposes to warn users about the negative performance >> impact of CC_OPTIMIZE_FOR_SIZE (compiling with -Os instead of -O2). >> For the moment, we are just advising users not to select this option, >> but extra details would be useful. >> >> I made some experiments with this option. All of them yielded >> degraded overall boot time. The kernel is smaller and hence is copied >> and started earlier, but the benefits are quickly offset by the >> slower kernel code. Even the total boot time is usually worse >> than with a regular kernel. >> >> Here are my latest results, on Atmel SAMA5D3 Xplained (ARM), >> Linux 3.10, gzip compressed kernel: >> >> Timestamp O2 Os Diff >> Starting kernel 4.307 s 5.593 s -94 ms >> Starting init 4.213 s 5.549 s -44 ms >> Login prompt 21.085 s 22.900 s +1.815 s > Did you get the times in the upper two rows transposed row/column? Based > on the diffs, I'd guess 4.213s goes in Os "Starting kernel", and 5.593s > goes in O2 "Starting init". Oops, yes I did. I shouldn't have tried to copy from a PDF file I produced ;) Thanks! Michael. -- Michael Opdenacker, CEO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- 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/
