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From: Martin KaFai Lau <kafai@fb.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: Dave Marchevsky <davemarchevsky@fb.com>,
	bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v6 bpf-next] selftests/bpf: Add benchmark for local_storage get
Date: Tue, 21 Jun 2022 17:29:52 -0700	[thread overview]
Message-ID: <20220622002952.6334ieb3kfysx7vl@kafai-mbp> (raw)
In-Reply-To: <62b21962dc64_1627420844@john.notmuch>

On Tue, Jun 21, 2022 at 12:17:54PM -0700, John Fastabend wrote:
> > Hashmap Control
> > ===============
> >         num keys: 10
> > hashmap (control) sequential    get:  hits throughput: 20.900 ± 0.334 M ops/s, hits latency: 47.847 ns/op, important_hits throughput: 20.900 ± 0.334 M ops/s
> > 
> >         num keys: 1000
> > hashmap (control) sequential    get:  hits throughput: 13.758 ± 0.219 M ops/s, hits latency: 72.683 ns/op, important_hits throughput: 13.758 ± 0.219 M ops/s
> > 
> >         num keys: 10000
> > hashmap (control) sequential    get:  hits throughput: 6.995 ± 0.034 M ops/s, hits latency: 142.959 ns/op, important_hits throughput: 6.995 ± 0.034 M ops/s
> > 
> >         num keys: 100000
> > hashmap (control) sequential    get:  hits throughput: 4.452 ± 0.371 M ops/s, hits latency: 224.635 ns/op, important_hits throughput: 4.452 ± 0.371 M ops/s
> > 
> >         num keys: 4194304
> > hashmap (control) sequential    get:  hits throughput: 3.043 ± 0.033 M ops/s, hits latency: 328.587 ns/op, important_hits throughput: 3.043 ± 0.033 M ops/s
> > 
> 
> Why is the hashmap lookup not constant with the number of keys? It looks
> like its prepopulated without collisions so I wouldn't expect any
> extra ops on the lookup side after looking at the code quickly.
It may be due to the cpu-cache misses as the map grows.

  reply	other threads:[~2022-06-22  0:30 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-20 22:25 [PATCH v6 bpf-next] selftests/bpf: Add benchmark for local_storage get Dave Marchevsky
2022-06-21 19:17 ` John Fastabend
2022-06-22  0:29   ` Martin KaFai Lau [this message]
2022-06-22  5:49     ` John Fastabend
2022-06-22 17:26       ` Martin KaFai Lau
2022-06-23  1:26         ` John Fastabend
2022-06-23  2:18           ` Alexei Starovoitov
2022-06-23  3:25             ` John Fastabend
2022-06-23  2:53           ` Dave Marchevsky
2022-06-23  3:27             ` John Fastabend
2022-06-23  2:31   ` Dave Marchevsky
2022-06-23  2:20 ` patchwork-bot+netdevbpf

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