Messages in this thread | | | Date | Thu, 10 Jun 2021 12:10:11 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH 1/1] lib: remove leading spaces before tabs |
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On Wed, Jun 09, 2021 at 02:44:54PM -0700, Joe Perches wrote: > On Wed, 2021-06-09 at 13:30 +0300, Andy Shevchenko wrote: > > On Wed, Jun 9, 2021 at 9:21 AM Leizhen (ThunderTown) > > <thunder.leizhen@huawei.com> wrote: > > > On 2021/6/9 13:15, Leizhen (ThunderTown) wrote: > > > > On 2021/6/9 0:03, Joe Perches wrote: > > > > > On Tue, 2021-06-08 at 17:00 +0800, Leizhen (ThunderTown) wrote: > > > > > > On 2021/6/8 16:44, Andy Shevchenko wrote: > > > > > > > On Tue, Jun 8, 2021 at 10:14 AM Zhen Lei <thunder.leizhen@huawei.com> wrote: > > > > > > > > > > > > > > > > 1) Run the following command to find and remove the leading spaces before > > > > > > > > tabs: > > > > > > > > find lib/ -type f | xargs sed -r -i 's/^[ ]+\t/\t/' > > > > > > > > > > > > > > Hint for the future, try to use what Git provides, for example `git > > > > > > > ls-files -- lib/`. > > > > > > > > > > > > Okay, thanks. I learned a new trick. > > > > > > > For instance: > > > > > > > > > > $ git diff --stat lib > > > > > $ git ls-files lib/ | \ > > > > > xargs ./scripts/checkpatch.pl --types=SPACE_BEFORE_TAB --fix-inplace > > > > > > I just tried it. It's too slow. > > > > If checkpath accepts infinite positional arguments, then proper way of > > use (that's how I do with simple perl regexps) is to > > > > scripts/checkpatch.pl --types=SPACE_BEFORE_TAB --fix-inplace -- $(git ls-files lib/) > > That won't always work: > > $ git ls-files | xargs | wc -c > 2716737 > > Nothing accepts infinite positional arguments. > You are always limited by the maximum length of a command line > > $ getconf ARG_MAX > 2097152 > > xargs has: > > $ xargs --show-limits > Your environment variables take up 3517 bytes > POSIX upper limit on argument length (this system): 2091587 > POSIX smallest allowable upper limit on argument length (all systems): 4096 > Maximum length of command we could actually use: 2088070 > Size of command buffer we are actually using: 131072 > Maximum parallelism (--max-procs must be no greater): 2147483647
If you care about parallelism, the checkpatch should be doing it itself.
Currently it's one perl interpreter with a single queue vs. zillions of perl invocations (with all downsides of this). And I'm not sure which one is a winning.
And yes, I'm aware of why xargs is ever exists (including handling of the special file names).
> > Seems like we have a shell lesson :-) > > Maybe so. > > Using xargs allows use of -P to invoke parallelism. > Or you could just use gnu parallel instead of xargs. > > Using './scripts/checkpatch.pl -- $(git ls-files <path>)' will only > allow a single process to be invoked for the files to be scanned.
-- With Best Regards, Andy Shevchenko
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