On Tue, Mar 06, 2018 at 08:27:33PM +0800, Aaron Lu wrote: > On Tue, Mar 06, 2018 at 08:55:57AM +0100, Vlastimil Babka wrote: > > So the adjacent line prefetch might be disabled? Could you check bios or > > the MSR mentioned in > > https://software.intel.com/en-us/articles/disclosure-of-hw-prefetcher-control-on-some-intel-processors > > root@lkp-bdw-ep2 ~# rdmsr 0x1a4 > 0
Technically 0x1a4 is per-core, so you should run rdmsr -a 0x1a4 in order to check all the cores. But I can't imagine they're being set differently on each core. > > instructions (calculated from itlb misses and insns-per-itlb-miss) shows > > less than 1% increase, so dunno. And the improvement comes from reduced > > dTLB-load-misses? That makes no sense for order-0 buddy struct pages > > which always share a page. And the memmap mapping should use huge pages. > > THP is disabled to stress order 0 pages(should have mentioned this in > patch's description, sorry about this). THP isn't related to memmap; the kernel uses huge pages (usually the 1G pages) in order to map its own memory.