On Wed 25-02-15 14:31:08, SeongJae Park wrote: > Hello Michal, > > Thanks for your comment :) > > On Tue, 24 Feb 2015, Michal Hocko wrote: > > >On Tue 24-02-15 04:54:18, SeongJae Park wrote: > >[...] > >> include/linux/cma.h | 4 + > >> include/linux/gcma.h | 64 +++ > >> mm/Kconfig | 24 + > >> mm/Makefile | 1 + > >> mm/cma.c | 113 ++++- > >> mm/gcma.c | 1321 ++++++++++++++++++++++++++++++++++++++++++++++++++ > >> 6 files changed, 1508 insertions(+), 19 deletions(-) > >> create mode 100644 include/linux/gcma.h > >> create mode 100644 mm/gcma.c > > > >Wow this is huge! And I do not see reason for it to be so big. Why > >cannot you simply define (per-cma area) 2-class users policy? Either via > >kernel command line or export areas to userspace and allow to set policy > >there. > > For implementation of the idea, we should develop not only policy selection, > but also backend for discardable memory. Most part of this patch were made > for the backend. What is the backend and why is it needed? I thought the discardable will go back to the CMA pool. I mean the cover email explained why the current CMA allocation policy might lead to lower success rate or stalls. So I would expect a new policy would be a relatively small change in the CMA allocation path to serve 2-class users as per policy. It is not clear to my why we need to pull a whole gcma layer in. I might be missing something obvious because I haven't looked at the patches yet but this should better be explained in the cover letter. Thanks! -- Michal Hocko SUSE Labs -- 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>