Messages in this thread | | | From | Andy Shevchenko <> | Date | Fri, 27 Jul 2018 13:39:22 +0300 | Subject | Re: [PATCH 1/1] lib: use sunday algorithm to do strstr() and strnstr() |
| |
On Fri, Jul 27, 2018 at 8:48 AM, Zhaoxiu Zeng <zengzhaoxiu@163.com> wrote: > 在 2018/7/27 1:17, Zhaoxiu Zeng 写道: >> 在 2018/7/23 2:37, Greg Kroah-Hartman 写道: >>> On Mon, Jul 23, 2018 at 01:37:15AM +0800, Zhaoxiu Zeng wrote:
>>>> The Sunday algorithm is a variation of Boyer-Moore algorithm, it is easy and fast. >>>> For the Sunday algorithm, to see >>>> http://www.inf.fh-flensburg.de/lang/algorithmen/pattern/sundayen.htm >>> >>> So you say, but what does this really buy us? Why make this change? >>> How was it tested? What is the downside of not taking this?
>> I use the following program to test on fc28. >> Compile with O2, the new version is almost 2X faster than the original.
>> The code size of the original is 0x80, the newer is 0xB0.
So, output of bloat-o-meter would be good to have in commit message.
>> The test result:
Compact performance statistics as well.
>> Thanks!
> The original strnstr might has a bug too! > For example, assume s1 is "123\0abc...." and s2 is "abc\0", > call strnstr(s1, s2, 7) will return &s1[4], but the correct result is NULL.
If there is a bug, send another patch to fix the bug first.
-- With Best Regards, Andy Shevchenko
| |