On Fri, 24 Feb 2017 19:40:31 +0800 Aaron Lu <aaron.lu@xxxxxxxxx> wrote: > For regular processes, the time taken in its exit() path to free its > used memory is not a problem. But there are heavy ones that consume > several Terabytes memory and the time taken to free its memory could > last more than ten minutes. > > To optimize this use case, a parallel free method is proposed here. > For detailed explanation, please refer to patch 2/5. > > I'm not sure if we need patch 4/5 which can avoid page accumulation > being interrupted in some case(patch description has more information). > My test case, which only deal with anon memory doesn't get any help out > of this of course. It can be safely dropped if it is deemed not useful. > > A test program that did a single malloc() of 320G memory is used to see > how useful the proposed parallel free solution is, the time calculated > is for the free() call. Test machine is a Haswell EX which has > 4nodes/72cores/144threads with 512G memory. All tests are done with THP > disabled. > > kernel time > v4.10 10.8s __2.8% > this patch(with default setting) 5.795s __5.8% Dumb question: why not do this in userspace, presumably as part of the malloc() library? malloc knows where all the memory is and should be able to kick off N threads to run around munmapping everything? -- 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>
