From: Akira Tsukamoto <akira.tsukamoto@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>,
Palmer Dabbelt <palmer@dabbelt.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Qiu Wenbo <qiuwenbo@kylinos.com.cn>,
Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/1] riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall
Date: Mon, 19 Jul 2021 23:00:13 +0900 [thread overview]
Message-ID: <e1bb4768-5517-8ef3-eaf3-bbfc103fa918@gmail.com> (raw)
In-Reply-To: <cd14a8b0-0a27-77a8-6dc2-3268f9f09922@roeck-us.net>
On 7/19/2021 10:51 PM, Guenter Roeck wrote:
> Hi,
>
> On 7/19/21 5:53 AM, Akira Tsukamoto wrote:
>>
>> This patch will reduce cpu usage dramatically in kernel space especially
>> for application which use sys-call with large buffer size, such as
>> network applications. The main reason behind this is that every
>> unaligned memory access will raise exceptions and switch between s-mode
>> and m-mode causing large overhead.
>>
>
> I had to revert the original patch from the mainline kernel prior to applying
> this patch. Obviously that means that there may be other changes affecting the
> outcome.
>
> riscv64 images work, but riscv32 images still fail with this patch applied.
> The error is a bit different than before, though.
>
> ...
> [ 11.899979] Run /sbin/init as init process
> [ 12.152666] random: fast init done
> moun: applet not found
> "�����V�t: applet not found
> /bi�����V�F-: applet not found
> moun: applet not found
> swaon: applet not found
> hostname-F: applet not found
>
> After this, the image hangs.
>
> For comparison, the mainline kernel (v5.14-rc2) fails as follows.
>
> [ 10.788105] Run /sbin/init as init process
> Starting syslogd: OK
> Starting klogd: OK
> /etc/init.d/S02sysctl: line 68: syntax error: EOF in backquote substitution
> /etc/init.d/S20urandom: line 1: syntax error: unterminated quoted string
> Starting network: /bin/sh: syntax error: unterminated quoted string
> sed: unmatched '/'
> /bin/sh: syntax error: unterminated quoted string
> FAIL
> /etc/init.d/S55runtest: line 48: syntax error: EOF in backquote substitution
>
> I'll be happy to provide information on how to reproduce the problem
> if needed. Please let me know.
Yes, I do would like to know the procedure of build instruction of your rv32 image.
Then I would reproduce the error and look into how to fix it.
Akira
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next prev parent reply other threads:[~2021-07-19 14:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 12:51 [PATCH v4 0/1] riscv: improving uaccess with logs from network bench Akira Tsukamoto
2021-07-19 12:53 ` [PATCH v4 1/1] riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall Akira Tsukamoto
2021-07-19 13:51 ` Guenter Roeck
2021-07-19 14:00 ` Akira Tsukamoto [this message]
2021-07-19 14:24 ` Guenter Roeck
2021-07-19 14:49 ` Akira Tsukamoto
2021-07-19 15:16 ` Guenter Roeck
2021-07-20 6:54 ` Akira Tsukamoto
2021-07-19 14:49 ` Geert Uytterhoeven
2021-07-19 15:22 ` Akira Tsukamoto
2021-07-19 14:55 ` [PATCH v4 0/1] riscv: improving uaccess with logs from network bench Akira Tsukamoto
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