On Tue, 10 Jan 2017 23:37:53 +0000 James Hartley <james.hartley@xxxxxxxxxx> wrote: > > On 06/01/17 22:43, Andrew Morton wrote: > > On Fri, 25 Nov 2016 18:55:18 +0000 Paul Burton <paul.burton@xxxxxxxxxx> wrote: > > > >> When using a sparse memory model memmap_init_zone() when invoked with > >> the MEMMAP_EARLY context will skip over pages which aren't valid - ie. > >> which aren't in a populated region of the sparse memory map. However if > >> the memory map is extremely sparse then it can spend a long time > >> linearly checking each PFN in a large non-populated region of the memory > >> map & skipping it in turn. > >> > >> When CONFIG_HAVE_MEMBLOCK_NODE_MAP is enabled, we have sufficient > >> information to quickly discover the next valid PFN given an invalid one > >> by searching through the list of memory regions & skipping forwards to > >> the first PFN covered by the memory region to the right of the > >> non-populated region. Implement this in order to speed up > >> memmap_init_zone() for systems with extremely sparse memory maps. > > Could we have a changelog which includes some timing measurements? > > That permits others to understand the value of this patch. > > > I have tested this patch on a virtual model of a Samurai CPU with a > sparse memory map. The kernel boot time drops from 109 to 62 seconds. Thanks. Nice. I updated the changelog. -- 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>