Messages in this thread | | | Subject | Re: [PATCH v2 bpf] bpf: Do not grab the bucket spinlock by default on htab batch ops | From | Yonghong Song <> | Date | Tue, 18 Feb 2020 13:23:15 -0800 |
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On 2/18/20 9:25 AM, Brian Vazquez wrote: > Grabbing the spinlock for every bucket even if it's empty, was causing > significant perfomance cost when traversing htab maps that have only a > few entries. This patch addresses the issue by checking first the > bucket_cnt, if the bucket has some entries then we go and grab the > spinlock and proceed with the batching. > > Tested with a htab of size 50K and different value of populated entries. > > Before: > Benchmark Time(ns) CPU(ns) > --------------------------------------------- > BM_DumpHashMap/1 2759655 2752033 > BM_DumpHashMap/10 2933722 2930825 > BM_DumpHashMap/200 3171680 3170265 > BM_DumpHashMap/500 3639607 3635511 > BM_DumpHashMap/1000 4369008 4364981 > BM_DumpHashMap/5k 11171919 11134028 > BM_DumpHashMap/20k 69150080 69033496 > BM_DumpHashMap/39k 190501036 190226162 > > After: > Benchmark Time(ns) CPU(ns) > --------------------------------------------- > BM_DumpHashMap/1 202707 200109 > BM_DumpHashMap/10 213441 210569 > BM_DumpHashMap/200 478641 472350 > BM_DumpHashMap/500 980061 967102 > BM_DumpHashMap/1000 1863835 1839575 > BM_DumpHashMap/5k 8961836 8902540 > BM_DumpHashMap/20k 69761497 69322756 > BM_DumpHashMap/39k 187437830 186551111 > > Fixes: 057996380a42 ("bpf: Add batch ops to all htab bpf map") > Cc: Yonghong Song <yhs@fb.com> > Signed-off-by: Brian Vazquez <brianvv@google.com>
Thanks for the fix. Acked-by: Yonghong Song <yhs@fb.com>
> --- > v1 -> v2: Skip hlist_nulls_for_each_entry_safe if lock is not held > > kernel/bpf/hashtab.c | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-)
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