From: David S. Miller Date: Tue, 8 Mar 2016 20:28:33 +0000 (-0500) Subject: Merge branch 'bpf-map-prealloc' X-Git-Tag: v4.6-rc1~91^2~108 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=f14b488d50b7dc234ddaed53ce4293c9eac47457;p=linux.git Merge branch 'bpf-map-prealloc' Alexei Starovoitov says: ==================== bpf: map pre-alloc v1->v2: . fix few issues spotted by Daniel . converted stackmap into pre-allocation as well . added a workaround for lockdep false positive . added pcpu_freelist_populate to be used by hashmap and stackmap this path set switches bpf hash map to use pre-allocation by default and introduces BPF_F_NO_PREALLOC flag to keep old behavior for cases where full map pre-allocation is too memory expensive. Some time back Daniel Wagner reported crashes when bpf hash map is used to compute time intervals between preempt_disable->preempt_enable and recently Tom Zanussi reported a dead lock in iovisor/bcc/funccount tool if it's used to count the number of invocations of kernel '*spin*' functions. Both problems are due to the recursive use of slub and can only be solved by pre-allocating all map elements. A lot of different solutions were considered. Many implemented, but at the end pre-allocation seems to be the only feasible answer. As far as pre-allocation goes it also was implemented 4 different ways: - simple free-list with single lock - percpu_ida with optimizations - blk-mq-tag variant customized for bpf use case - percpu_freelist For bpf style of alloc/free patterns percpu_freelist is the best and implemented in this patch set. Detailed performance numbers in patch 3. Patch 2 introduces percpu_freelist Patch 1 fixes simple deadlocks due to missing recursion checks Patch 5: converts stackmap to pre-allocation Patches 6-9: prepare test infra Patch 10: stress test for hash map infra. It attaches to spin_lock functions and bpf_map_update/delete are called from different contexts Patch 11: stress for bpf_get_stackid Patch 12: map performance test Reported-by: Daniel Wagner Reported-by: Tom Zanussi ==================== Signed-off-by: David S. Miller --- f14b488d50b7dc234ddaed53ce4293c9eac47457