From: John Fastabend <john.fastabend@gmail.com>
To: Martin KaFai Lau <kafai@fb.com>,
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 22:49:46 -0700 [thread overview]
Message-ID: <62b2ad7a21e88_34dc820812@john.notmuch> (raw)
In-Reply-To: <20220622002952.6334ieb3kfysx7vl@kafai-mbp>
Martin KaFai Lau wrote:
> 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.
Maybe but, values are just ints so even 1k * 4B = 4kB should be
inside an otherwise unused server class system. Would be more
believable (to me at least) if the drop off happened at 100k or
more.
next prev parent reply other threads:[~2022-06-22 5:49 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
2022-06-22 5:49 ` John Fastabend [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=62b2ad7a21e88_34dc820812@john.notmuch \
--to=john.fastabend@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davemarchevsky@fb.com \
--cc=kafai@fb.com \
--cc=kernel-team@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox