From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: Brian Vazquez <brianvv@google.com>,
Brian Vazquez <brianvv.kernel@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"David S . Miller" <davem@davemloft.net>,
LKML <linux-kernel@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH v2 bpf] bpf: Do not grab the bucket spinlock by default on htab batch ops
Date: Wed, 19 Feb 2020 15:12:06 -0800 [thread overview]
Message-ID: <CAADnVQJofPTYg73qoY6e-SwgyrtqPwU9JKx8DQ-9+L_uW6=X9g@mail.gmail.com> (raw)
In-Reply-To: <c31be4c5-d4c7-5979-215e-de23b9ca0549@fb.com>
On Tue, Feb 18, 2020 at 1:23 PM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> 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>
Applied. Thanks
prev parent reply other threads:[~2020-02-19 23:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 17:25 [PATCH v2 bpf] bpf: Do not grab the bucket spinlock by default on htab batch ops Brian Vazquez
2020-02-18 21:23 ` Yonghong Song
2020-02-19 23:12 ` Alexei Starovoitov [this message]
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