> > Hello, Joel. > > > > First of all thank you for improving it. I also noticed a high pressure > > on RCU-machinery during performing some vmalloc tests when kfree_rcu() > > flood occurred. Therefore i got rid of using kfree_rcu() there. > > Replying a bit late due to overseas conference travel and vacation. > > When you say 'high pressure', do you mean memory pressure or just system > load? > > > Memory pressure slightly increases with the kfree_rcu() rework with the > benefit of much fewer grace periods. > I meant a system load, because of high number of cycles in the kfree_rcu() symbol under stressing. But i do not have numbers next to me, because it was quite a long time ago. As for memory usage, i understand that. > > I have just a small question related to workloads and performance evaluation. > > Are you aware of any specific workloads which benefit from it for example > > mobile area, etc? I am asking because i think about backporting of it and > > reuse it on our kernel. > > I am not aware of a mobile usecase that benefits but there are server > workloads that make system more stable in the face of a kfree_rcu() flood. > OK, i got it. I wanted to test it finding out how it could effect mobile workloads. > > For the KVA allocator work, I see it is quite similar to the way binder > allocates blocks. See function: binder_alloc_new_buf_locked(). Is there are > any chance to reuse any code? For one thing, binder also has an rbtree for > allocated blocks for fast lookup of allocated blocks. Does the KVA allocator > not have the need for that? > Well, there is a difference. Actually the free blocks are not sorted by the its size like in binder layer, if understand the code correctly. Instead, i keep them(free blocks) sorted(by start address) in ascending order + maintain the augment value(biggest free size in left or right sub-tree) for each node, that allows to navigate toward the lowest address and the block that definitely suits. So as a result our allocations become sequential what is important. > > And, nice LPC presentation! I was there ;) > Thanks :) -- Vlad Rezki
