On Wed, Aug 14, 2013 at 02:31:45PM -0500, Seth Jennings wrote: > Large memory systems (~1TB or more) experience boot delays on the order > of minutes due to the initializing the memory configuration part of > sysfs at /sys/devices/system/memory/. Are you sure that is the problem area? Have you run perf on it? > ppc64 has a normal memory block size of 256M (however sometimes as low > as 16M depending on the system LMB size), and (I think) x86 is 128M. With > 1TB of RAM and a 256M block size, that's 4k memory blocks with 20 sysfs > entries per block that's around 80k items that need be created at boot > time in sysfs. Some systems go up to 16TB where the issue is even more > severe. The x86 developers are working with larger memory sizes and they haven't seen the problem in this area, for them it's in other places, as I referred to in my other email. > This patch provides a means by which users can prevent the creation of > the memory block attributes at boot time, yet still dynamically create > them if they are needed. > > This patch creates a new boot parameter, "largememory" that will prevent > memory_dev_init() from creating all of the memory block sysfs attributes > at boot time. Instead, a new root attribute "show" will allow > the dynamic creation of the memory block devices. > Another new root attribute "present" shows the memory blocks present in > the system; the valid inputs for the "show" attribute. You never documented any of these abi changes, which is a requirement (not that I'm agreeing that a boot parameter is ok...) > There was a significant amount of refactoring to allow for this but > IMHO, the code is much easier to understand now. Care to refactor things first, with no logical changes, and then make your changes in a follow-on patch, so that people can actually find what you changed in the patch? Remember, a series of patches please, not one big "refactor and change it all" patch. thanks, greg k-h -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>