All of lore.kernel.org
 help / color / mirror / Atom feed
From: Yao Zi <me@ziyao.cc>
To: guoren@kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com,
	alex@ghiti.fr, leobras@redhat.com,
	djordje.todorovic@htecgroup.com, aleksa.paunovic@htecgroup.com,
	arnd@arndb.de, rabenda.cn@gmail.com
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org, Han Gao <gaohan@iscas.ac.cn>,
	Alexandre Ghiti <alexghiti@rivosinc.com>,
	Paul Walmsley <pjw@kernel.org>
Subject: Re: [PATCH V3] riscv: errata: Add ERRATA_THEAD_WRITE_ONCE fixup
Date: Thu, 19 Feb 2026 08:04:42 +0000	[thread overview]
Message-ID: <aZbEGsqXSQzORQ__@pie> (raw)
In-Reply-To: <20260125063941.443777-1-guoren@kernel.org>

On Sun, Jan 25, 2026 at 01:39:41AM -0500, guoren@kernel.org wrote:
> From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
> 
> The early version of XuanTie C910 core has a store merge buffer
> delay problem. The store merge buffer could improve the store queue
> performance by merging multi-store requests, but when there are not
> continued store requests, the prior single store request would be
> waiting in the store queue for a long time. That would cause
> significant problems for communication between multi-cores. This
> problem was found on sg2042 & th1520 platforms with the qspinlock
> lock torture test.
> 
> So appending a fence w.o could immediately flush the store merge
> buffer and let other cores see the write result.
> 
> This will apply the WRITE_ONCE errata to handle the non-standard
> behavior via appending a fence w.o instruction for WRITE_ONCE().
> 
> This problem is only observed on the sg2042 hardware platform by
> running the lock_torture test program for half an hour. The problem
> was not found in the user space application, because interrupt can
> break the livelock.
> 
> Reviewed-by: Leonardo Bras <leobras@redhat.com>
> Tested-by: Han Gao <gaohan@iscas.ac.cn>
> Cc: Yao Zi <me@ziyao.cc>
> Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
> Cc: Paul Walmsley <pjw@kernel.org>
> Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>

With the patch, I've run heavy multi-core compilation load on SG2042 for
more than 12 hours, and observed no stability issues.

Tested-by: Yao Zi <me@ziyao.cc>

Thanks,
Yao Zi

WARNING: multiple messages have this Message-ID (diff)
From: Yao Zi <me@ziyao.cc>
To: guoren@kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com,
	alex@ghiti.fr, leobras@redhat.com,
	djordje.todorovic@htecgroup.com, aleksa.paunovic@htecgroup.com,
	arnd@arndb.de, rabenda.cn@gmail.com
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org, Han Gao <gaohan@iscas.ac.cn>,
	Alexandre Ghiti <alexghiti@rivosinc.com>,
	Paul Walmsley <pjw@kernel.org>
Subject: Re: [PATCH V3] riscv: errata: Add ERRATA_THEAD_WRITE_ONCE fixup
Date: Thu, 19 Feb 2026 08:04:42 +0000	[thread overview]
Message-ID: <aZbEGsqXSQzORQ__@pie> (raw)
In-Reply-To: <20260125063941.443777-1-guoren@kernel.org>

On Sun, Jan 25, 2026 at 01:39:41AM -0500, guoren@kernel.org wrote:
> From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>
> 
> The early version of XuanTie C910 core has a store merge buffer
> delay problem. The store merge buffer could improve the store queue
> performance by merging multi-store requests, but when there are not
> continued store requests, the prior single store request would be
> waiting in the store queue for a long time. That would cause
> significant problems for communication between multi-cores. This
> problem was found on sg2042 & th1520 platforms with the qspinlock
> lock torture test.
> 
> So appending a fence w.o could immediately flush the store merge
> buffer and let other cores see the write result.
> 
> This will apply the WRITE_ONCE errata to handle the non-standard
> behavior via appending a fence w.o instruction for WRITE_ONCE().
> 
> This problem is only observed on the sg2042 hardware platform by
> running the lock_torture test program for half an hour. The problem
> was not found in the user space application, because interrupt can
> break the livelock.
> 
> Reviewed-by: Leonardo Bras <leobras@redhat.com>
> Tested-by: Han Gao <gaohan@iscas.ac.cn>
> Cc: Yao Zi <me@ziyao.cc>
> Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
> Cc: Paul Walmsley <pjw@kernel.org>
> Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren@kernel.org>

With the patch, I've run heavy multi-core compilation load on SG2042 for
more than 12 hours, and observed no stability issues.

Tested-by: Yao Zi <me@ziyao.cc>

Thanks,
Yao Zi

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply	other threads:[~2026-02-19  8:05 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-25  6:39 [PATCH V3] riscv: errata: Add ERRATA_THEAD_WRITE_ONCE fixup guoren
2026-01-25  6:39 ` guoren
2026-02-18 12:06 ` Han Gao
2026-02-18 12:06   ` Han Gao
2026-02-19  8:04 ` Yao Zi [this message]
2026-02-19  8:04   ` Yao Zi
2026-02-24  2:04   ` Guo Ren
2026-02-24  2:04     ` Guo Ren

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=aZbEGsqXSQzORQ__@pie \
    --to=me@ziyao.cc \
    --cc=aleksa.paunovic@htecgroup.com \
    --cc=alex@ghiti.fr \
    --cc=alexghiti@rivosinc.com \
    --cc=arnd@arndb.de \
    --cc=djordje.todorovic@htecgroup.com \
    --cc=gaohan@iscas.ac.cn \
    --cc=guoren@kernel.org \
    --cc=leobras@redhat.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=palmer@dabbelt.com \
    --cc=paul.walmsley@sifive.com \
    --cc=pjw@kernel.org \
    --cc=rabenda.cn@gmail.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.