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[PATCH v2 0/3] bpf: hash: use per-bucket spinlock

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Hi,

This patchset tries to optimize ebpf hash map, and follows
the idea:

        Both htab_map_update_elem() and htab_map_delete_elem()
        can be called from eBPF program, and they may be in kernel
        hot path, it isn't efficient to use a per-hashtable lock
        in this two helpers, so this patch converts the lock into
        per-bucket spinlock.

With this patchset, looks the performance penalty from eBPF
decreased a lot, see the following test:

        1) run 'tools/biolatency' of bcc before running block test;

        2) run fio to test block throught over /dev/nullb0,
        (randread, 16jobs, libaio, 4k bs) and the test box
        is one 24cores(dual sockets) VM server:
        - without patchset:  607K IOPS
        - with this patchset: 1184K IOPS
        - without running eBPF prog: 1492K IOPS

TODO:
        - remove the per-hashtable atomic counter

V2:
        - fix checking on buckets size
V1:
        - fix the wrong 3/3 patch

 kernel/bpf/hashtab.c | 64 +++++++++++++++++++++++++++++++---------------------
 1 file changed, 38 insertions(+), 26 deletions(-)

Thanks,
Ming Lei


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[PATCH v2 0/3] bpf: hash: use per-bucket spinlock  Ming Lei <tom.leiming@gmail.com> - 2015-12-29 15:50 +0100
  [PATCH v2 1/3] bpf: hash: use atomic count Ming Lei <tom.leiming@gmail.com> - 2015-12-29 15:50 +0100
  [PATCH v2 2/3] bpf: hash: move select_bucket() out of htab's spinlock Ming Lei <tom.leiming@gmail.com> - 2015-12-29 15:50 +0100
  [PATCH v2 3/3] bpf: hash: use per-bucket spinlock Ming Lei <tom.leiming@gmail.com> - 2015-12-29 16:00 +0100
    Re: [PATCH v2 3/3] bpf: hash: use per-bucket spinlock Daniel Borkmann <daniel@iogearbox.net> - 2015-12-29 17:30 +0100
  Re: [PATCH v2 0/3] bpf: hash: use per-bucket spinlock  David Miller <davem@davemloft.net> - 2015-12-29 21:20 +0100

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