Hi Yasuaki, Forgot to mention that I have no objection to this patchset. I think it's a good start point, but we still need to improve usabilities of memory hotplug by passing platform specific information from BIOS. And mechanism provided by this patchset will/may be used to improve usabilities too. Regards! Gerry On 11/29/2012 06:38 PM, Yasuaki Ishimatsu wrote: > Hi Tony, > > 2012/11/29 6:34, Luck, Tony wrote: >>> 1. use firmware information >>> According to ACPI spec 5.0, SRAT table has memory affinity structure >>> and the structure has Hot Pluggable Filed. See "5.2.16.2 Memory >>> Affinity Structure". If we use the information, we might be able to >>> specify movable memory by firmware. For example, if Hot Pluggable >>> Filed is enabled, Linux sets the memory as movable memory. >>> >>> 2. use boot option >>> This is our proposal. New boot option can specify memory range to use >>> as movable memory. >> >> Isn't this just moving the work to the user? To pick good values for the > > Yes. > >> movable areas, they need to know how the memory lines up across >> node boundaries ... because they need to make sure to allow some >> non-movable memory allocations on each node so that the kernel can >> take advantage of node locality. > > There is no problem. > Linux has already two boot options, kernelcore= and movablecore=. > So if we use them, non-movable memory is divided into each node evenly. > > But there is no way to specify a node used as movable currently. So > we proposed the new boot option. > >> So the user would have to read at least the SRAT table, and perhaps >> more, to figure out what to provide as arguments. >> > >> Since this is going to be used on a dynamic system where nodes might >> be added an removed - the right values for these arguments might >> change from one boot to the next. So even if the user gets them right >> on day 1, a month later when a new node has been added, or a broken >> node removed the values would be stale. > > I don't think so. Even if we hot add/remove node, the memory range of > each memory device is not changed. So we don't need to change the boot > option. > > Thanks, > Yasuaki Ishimatsu > >> >> -Tony >> > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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>