From: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
bpf@vger.kernel.org, Daniel Borkmann <daniel@iogearbox.net>,
Hao Luo <haoluo@google.com>,
John Fastabend <john.fastabend@gmail.com>,
Jiri Olsa <jolsa@kernel.org>, KP Singh <kpsingh@kernel.org>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
Martin KaFai Lau <martin.lau@linux.dev>,
Stanislav Fomichev <sdf@google.com>, Song Liu <song@kernel.org>,
Yonghong Song <yhs@fb.com>
Subject: Re: [PATCH] powerpc/bpf: Only update ldimm64 during extra pass when it is an address
Date: Thu, 24 Nov 2022 15:43:50 +0530 [thread overview]
Message-ID: <1669284441.66eunvaboi.naveen@linux.ibm.com> (raw)
In-Reply-To: <3f6d302a2068d9e357efda2d92c8da99a0f2d0b2.1669278892.git.christophe.leroy@csgroup.eu>
Christophe Leroy wrote:
> ldimm64 is not only used for loading function addresses, and
That's probably true today, but I worry that that can change upstream
and we may not notice at all.
> the NOPs added for padding are impacting performance, so avoid
> them when not necessary.
>
> On QEMU mac99, with the patch:
>
> test_bpf: #829 ALU64_MOV_K: all immediate value magnitudes jited:1 167436810 PASS
> test_bpf: #831 ALU64_OR_K: all immediate value magnitudes jited:1 170702940 PASS
>
> Without the patch:
>
> test_bpf: #829 ALU64_MOV_K: all immediate value magnitudes jited:1 173012360 PASS
> test_bpf: #831 ALU64_OR_K: all immediate value magnitudes jited:1 176424090 PASS
>
> That's a 3.5% performance improvement.
A better approach would be to do a full JIT during the extra pass.
That's what most other architectures do today. And, as long as we can
ensure that the JIT'ed program size can never increase during the
extra pass, we should be ok to do a single extra pass.
- Naveen
next prev parent reply other threads:[~2022-11-24 10:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-24 8:39 [PATCH] powerpc/bpf: Only update ldimm64 during extra pass when it is an address Christophe Leroy
2022-11-24 10:13 ` Naveen N. Rao [this message]
2022-11-24 12:24 ` Christophe Leroy
2022-11-24 13:49 ` Naveen N. Rao
2022-11-24 19:46 ` Christophe Leroy
2022-11-25 5:38 ` Naveen N. Rao
2022-11-25 5:59 ` Christophe Leroy
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=1669284441.66eunvaboi.naveen@linux.ibm.com \
--to=naveen.n.rao@linux.ibm.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=christophe.leroy@csgroup.eu \
--cc=daniel@iogearbox.net \
--cc=haoluo@google.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kpsingh@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=martin.lau@linux.dev \
--cc=mpe@ellerman.id.au \
--cc=npiggin@gmail.com \
--cc=sdf@google.com \
--cc=song@kernel.org \
--cc=yhs@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