From: "Radim Krčmář" <rkrcmar@ventanamicro.com>
To: "yunhui cui" <cuiyunhui@bytedance.com>
Cc: <masahiroy@kernel.org>, <nathan@kernel.org>,
<nicolas.schier@linux.dev>, <dennis@kernel.org>, <tj@kernel.org>,
<cl@gentwo.org>, <paul.walmsley@sifive.com>, <palmer@dabbelt.com>,
<aou@eecs.berkeley.edu>, <alex@ghiti.fr>, <andybnac@gmail.com>,
<bjorn@rivosinc.com>, <cyrilbur@tenstorrent.com>,
<rostedt@goodmis.org>, <puranjay@kernel.org>,
<ben.dooks@codethink.co.uk>, <zhangchunyan@iscas.ac.cn>,
<ruanjinjie@huawei.com>, <jszhang@kernel.org>,
<charlie@rivosinc.com>, <cleger@rivosinc.com>,
<antonb@tenstorrent.com>, <ajones@ventanamicro.com>,
<debug@rivosinc.com>, <haibo1.xu@intel.com>,
<samuel.holland@sifive.com>, <linux-kbuild@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<linux-riscv@lists.infradead.org>,
"linux-riscv" <linux-riscv-bounces@lists.infradead.org>,
<wangziang.ok@bytedance.com>
Subject: Re: [External] [PATCH] RISC-V: store percpu offset in CSR_SCRATCH
Date: Wed, 09 Jul 2025 16:20:38 +0200 [thread overview]
Message-ID: <DB7L9ZHZI3AI.36SXWX2SO9OS7@ventanamicro.com> (raw)
In-Reply-To: <CAEEQ3wkoy3Jr0vZk=X4U56KYPq3=5t7Wr4RE6uNby3MS5qzh-g@mail.gmail.com>
2025-07-09T19:42:26+08:00, yunhui cui <cuiyunhui@bytedance.com>:
> Bench platform: Spacemit(R) X60
> No changes:
> 6.77, 6.791, 6.792, 6.826, 6.784, 6.839, 6.776, 6.733, 6.795, 6.763
> Geometric mean: 6.786839305
> Reusing the current scratch:
> 7.085, 7.09, 7.021, 7.089, 7.068, 7.034, 7.06, 7.062, 7.065, 7.051
> Geometric mean: 7.062466876
Great results.
> A degradation of approximately 4.06% is observed. The possible cause
> of the degradation is that the CSR_TVEC register is set every time a
> kernel/user exception occurs.
I assume the same.
> The following is the patch without percpu optimization, which only
> tests the overhead of separating exceptions into kernel and user
> modes.
Is the overhead above with this patch? And when we then use the
CSR_SCRATCH for percpu, does it degrade even further?
Thanks.
next prev parent reply other threads:[~2025-07-09 14:20 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-04 8:45 [PATCH RFC] RISC-V: Fix a register to store the percpu offset Yunhui Cui
2025-07-07 7:55 ` Clément Léger
2025-07-07 12:50 ` [PATCH] RISC-V: store percpu offset in CSR_SCRATCH Radim Krčmář
2025-07-08 10:07 ` [External] " yunhui cui
2025-07-08 11:10 ` Radim Krčmář
2025-07-09 11:42 ` yunhui cui
2025-07-09 14:20 ` Radim Krčmář [this message]
2025-07-10 3:45 ` yunhui cui
2025-07-10 6:35 ` Radim Krčmář
2025-07-10 11:47 ` yunhui cui
2025-07-10 16:40 ` [PATCH] RISC-V: store precomputed percpu_offset in the task struct Radim Krčmář
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=DB7L9ZHZI3AI.36SXWX2SO9OS7@ventanamicro.com \
--to=rkrcmar@ventanamicro.com \
--cc=ajones@ventanamicro.com \
--cc=alex@ghiti.fr \
--cc=andybnac@gmail.com \
--cc=antonb@tenstorrent.com \
--cc=aou@eecs.berkeley.edu \
--cc=ben.dooks@codethink.co.uk \
--cc=bjorn@rivosinc.com \
--cc=charlie@rivosinc.com \
--cc=cl@gentwo.org \
--cc=cleger@rivosinc.com \
--cc=cuiyunhui@bytedance.com \
--cc=cyrilbur@tenstorrent.com \
--cc=debug@rivosinc.com \
--cc=dennis@kernel.org \
--cc=haibo1.xu@intel.com \
--cc=jszhang@kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-riscv-bounces@lists.infradead.org \
--cc=linux-riscv@lists.infradead.org \
--cc=masahiroy@kernel.org \
--cc=nathan@kernel.org \
--cc=nicolas.schier@linux.dev \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=puranjay@kernel.org \
--cc=rostedt@goodmis.org \
--cc=ruanjinjie@huawei.com \
--cc=samuel.holland@sifive.com \
--cc=tj@kernel.org \
--cc=wangziang.ok@bytedance.com \
--cc=zhangchunyan@iscas.ac.cn \
/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