On Wed, 5 Mar 2014, Greg KH wrote: > On Tue, Mar 04, 2014 at 07:01:49PM -0500, Jon Ringle wrote: > > +config CC_OPTIMIZE_FOR_SPEED > > + bool "Optimze for speed (-O3)" > > + help > > + Enabling this option will pass "-O3" to gcc > > + resulting in a larger kernel (but possibly faster) > > Are you sure about that? Have you measured it?
(Resending this message, since it was "destroyed". Hopefully, this is now an an acceptable form :) I do know that there is an improvement performance-wise for my particular use-case. My target is an ARM board being built with gcc-4.8.2. My board has on it a sc16is740 that is used as an RS-485 port. The sc16is740 is on the i2c bus, so when an interrupt comes in to indicate that there is data available to be read, I need to get the data over the i2c bus. I do this on a kthread to do this work. The i2c transactions (using i2c-davinci driver) are also interrupt driven. I was seeing a lot of lost packets when receiving data at only 19200. Adding the -O3 compile option helped in this regard in that I am now rarely seeing packet loss. Jon -- 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/
