Messages in this thread | | | From | Guenter Roeck <> | Subject | Re: [PATCH v4 1/1] riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall | Date | Mon, 19 Jul 2021 07:24:44 -0700 |
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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, Guenter
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