On 08/30/2016 12:44 PM, Anshuman Khandual wrote: > On 08/30/2016 09:09 AM, Andrew Morton wrote: >> On Tue, 30 Aug 2016 11:09:15 +0800 Aaron Lu <aaron.lu@xxxxxxxxx> wrote: >> >>>>> Case used for test on Haswell EP: >>>>> usemem -n 72 --readonly -j 0x200000 100G >>>>> Which spawns 72 processes and each will mmap 100G anonymous space and >>>>> then do read only access to that space sequentially with a step of 2MB. >>>>> >>>>> perf report for base commit: >>>>> 54.03% usemem [kernel.kallsyms] [k] get_huge_zero_page >>>>> perf report for this commit: >>>>> 0.11% usemem [kernel.kallsyms] [k] mm_get_huge_zero_page >>>> >>>> Does this mean that overall usemem runtime halved? >>> >>> Sorry for the confusion, the above line is extracted from perf report. >>> It shows the percent of CPU cycles executed in a specific function. >>> >>> The above two perf lines are used to show get_huge_zero_page doesn't >>> consume that much CPU cycles after applying the patch. >>> >>>> >>>> Do we have any numbers for something which is more real-wordly? >>> >>> Unfortunately, no real world numbers. >>> >>> We think the global atomic counter could be an issue for performance >>> so I'm trying to solve the problem. >> >> So, umm, we don't actually know if the patch is useful to anyone? > > On a POWER system it improves the CPU consumption of the above mentioned > function a little bit. Dont think its going to improve actual throughput > of the workload substantially. > > 0.07% usemem [kernel.vmlinux] [k] mm_get_huge_zero_page I guess this is the base commit? But there shouldn't be the new mm_get_huge_zero_page symbol before this patch. A typo perhaps? Regards, Aaron > to > > 0.01% usemem [kernel.vmlinux] [k] mm_get_huge_zero_page > -- 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>