Messages in this thread | | | Subject | Re: [PATCH v4 1/1] riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall | From | Akira Tsukamoto <> | Date | Mon, 19 Jul 2021 23:49:53 +0900 |
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On 7/19/2021 11:24 PM, Guenter Roeck wrote: > On 7/19/21 7:00 AM, Akira Tsukamoto wrote: >> >> 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. >> > Please have a look at http://server.roeck-us.net/qemu/riscv32/ > and let me know if you need anything else.
Thanks for the link. I will work on it tomorrow in my time. Building the kernel with defconfig looks much quicker than the config. I will try it from defconfig and then config.
Also I would like to use the same rv32 toolchain. Are you using prebuilt riscv32-linux-gcc? Should not make differences but just in case.
Is there a public reference for the way of building your qemu and opensbi? Not sure which version of qemu with which rv32 to build them, rv32i, rv32imad or else.
I really appreciate your help.
Akira
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