On Thu, Jul 6, 2023 at 6:45 PM Hou Tao <houtao@xxxxxxxxxxxxxxx> wrote: > > > > On 7/6/2023 11:34 AM, Alexei Starovoitov wrote: > > From: Alexei Starovoitov <ast@xxxxxxxxxx> > > > > Introduce bpf_mem_[cache_]free_rcu() similar to kfree_rcu(). > > Unlike bpf_mem_[cache_]free() that links objects for immediate reuse into > > per-cpu free list the _rcu() flavor waits for RCU grace period and then moves > > objects into free_by_rcu_ttrace list where they are waiting for RCU > > task trace grace period to be freed into slab. > > > > The life cycle of objects: > > alloc: dequeue free_llist > > free: enqeueu free_llist > > free_rcu: enqueue free_by_rcu -> waiting_for_gp > > free_llist above high watermark -> free_by_rcu_ttrace > > after RCU GP waiting_for_gp -> free_by_rcu_ttrace > > free_by_rcu_ttrace -> waiting_for_gp_ttrace -> slab > > > > Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> > > Acked-by: Hou Tao <houtao1@xxxxxxxxxx> Thank you very much for code reviews and feedback. btw I still believe that ABA is a non issue and prefer to keep the code as-is, but for the sake of experiment I've converted it to spin_lock (see attached patch which I think uglifies the code) and performance across bench htab-mem and map_perf_test seems to be about the same. Which was a bit surprising to me. Could you please benchmark it on your system?
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0001-bpf-Address-hypothetical-ABA-issue-with-llist_del_fi.patch
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