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". - Josh Triplett -- 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/
