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 08:16:52 -0700 |
| |
On 7/19/21 7:49 AM, Akira Tsukamoto wrote: > > 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. >
I use a toolchain built with either buildroot (when building the root file system) or with the buildall scripts from https://github.com/jmesmon/buildall.git (for the kernel). Either case, it is the default riscv32 toolchain from both.
> 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 don't know about rv32i or rv32imad, sorry. I build qemu from source using --disable-user --disable-gnutls --disable-docs \ --disable-nettle --disable-gcrypt --disable-vnc-png \ --disable-xen --disable-xen-pci-passthrough \ --disable-libssh configuration options. The firmware image (opensbi) is built as part of that. You should be able to use a pre-built version of qemu v6.0 if that is available somewhere.
Hope this helps, Guenter
| |