From: Xu Lu <luxu.kernel@bytedance.com>
To: paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, andy.chiu@sifive.com, guoren@kernel.org
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
lihangjing@bytedance.com, dengliang.1214@bytedance.com,
xieyongji@bytedance.com, chaiwen.cc@bytedance.com,
Xu Lu <luxu.kernel@bytedance.com>
Subject: [RFC 0/2] riscv: Idle thread using Zawrs extension
Date: Thu, 18 Apr 2024 19:49:40 +0800 [thread overview]
Message-ID: <20240418114942.52770-1-luxu.kernel@bytedance.com> (raw)
This patch series introduces a new implementation of idle thread using
Zawrs extension.
The Zawrs[0] extension introduces two new instructions named WRS.STO and
WRS.NTO in RISC-V. When software registers a reservation set using LR
instruction, a subsequent WRS.STO or WRS.NTO instruction will cause the
hart to stall in a low-power state until a store happens to the
reservation set or an interrupt becomes pending. The difference between
these two instructions is that WRS.STO will terminate stall after an
implementation-defined timeout while WRS.NTO won't.
This patch series implements idle thread using WRS.NTO instruction.
Besides, we found there is no need to send a real IPI to wake up an idle
CPU. Instead, we write IPI information to the reservation set of an idle
CPU to wake it up and let it handle IPI quickly, without going through
tranditional interrupt handling routine.
[0] https://github.com/riscv/riscv-zawrs/blob/main/zawrs.adoc
Xu Lu (2):
riscv: process: Introduce idle thread using Zawrs extension
riscv: Use Zawrs to accelerate IPI to idle cpu
arch/riscv/Kconfig | 24 +++++++
arch/riscv/include/asm/cpuidle.h | 11 +---
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/include/asm/processor.h | 31 +++++++++
arch/riscv/include/asm/smp.h | 14 ++++
arch/riscv/kernel/cpu.c | 5 ++
arch/riscv/kernel/cpufeature.c | 1 +
arch/riscv/kernel/process.c | 102 ++++++++++++++++++++++++++++-
arch/riscv/kernel/smp.c | 39 +++++++----
9 files changed, 205 insertions(+), 23 deletions(-)
--
2.20.1
next reply other threads:[~2024-04-18 11:49 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-18 11:49 Xu Lu [this message]
2024-04-18 11:49 ` [RFC 1/2] riscv: process: Introduce idle thread using Zawrs extension Xu Lu
2024-04-18 15:05 ` Conor Dooley
2024-04-18 16:14 ` [External] " Xu Lu
2024-04-22 8:21 ` Conor Dooley
2024-04-18 19:10 ` Andrew Jones
2024-04-18 22:00 ` Samuel Holland
2024-04-18 22:09 ` Conor Dooley
2024-04-18 11:49 ` [RFC 2/2] riscv: Use Zawrs to accelerate IPI to idle cpu Xu Lu
2024-04-18 12:26 ` [RFC 0/2] riscv: Idle thread using Zawrs extension Christoph Müllner
2024-04-18 12:44 ` [External] " Xu Lu
2024-04-18 12:56 ` Christoph Müllner
2024-04-18 13:09 ` Xu Lu
2024-04-18 14:08 ` Conor Dooley
2024-04-18 14:10 ` Andrew Jones
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=20240418114942.52770-1-luxu.kernel@bytedance.com \
--to=luxu.kernel@bytedance.com \
--cc=andy.chiu@sifive.com \
--cc=aou@eecs.berkeley.edu \
--cc=chaiwen.cc@bytedance.com \
--cc=dengliang.1214@bytedance.com \
--cc=guoren@kernel.org \
--cc=lihangjing@bytedance.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=xieyongji@bytedance.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;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).