> -----Original Message----- > From: netdev-ow...@vger.kernel.org [mailto:netdev- > ow...@vger.kernel.org] On Behalf Of Joe Perches > Sent: Saturday, September 16, 2017 06:18 > To: Ying Xue <ying....@windriver.com>; Thomas Meyer > <tho...@m3y3r.de>; Jon Maloy <jon.ma...@ericsson.com>; > net...@vger.kernel.org; tipc-discuss...@lists.sourceforge.net; linux- > ker...@vger.kernel.org; da...@davemloft.net > Subject: Re: [PATCH V2] tipc: Use bsearch library function > > On Sat, 2017-09-16 at 18:10 +0800, Ying Xue wrote: > > On 09/16/2017 05:58 PM, Joe Perches wrote: > > > On Sat, 2017-09-16 at 17:36 +0800, Ying Xue wrote: > > > > On 09/16/2017 05:26 PM, Joe Perches wrote: > > > > > On Sat, 2017-09-16 at 17:02 +0800, Ying Xue wrote: > > > > > > On 09/16/2017 03:50 PM, Thomas Meyer wrote: > > > > > > > Use common library function rather than explicitly coding > > > > > > > some variant of it yourself. > > > > > > > > > > > > > > Signed-off-by: Thomas Meyer <tho...@m3y3r.de> > > > > > > > > > > > > Acked-by: Ying Xue <ying....@windriver.com> > > > > > > > > > > Are you sure you want to do this? > > > > > > > > > > Note the comment above nameseq_find_subseq > > > > > > > > > > * Very time-critical, so binary searches through sub-sequence array. > > > > > > > > > > What impact does this change have on performance? > > > > > > > > Sorry, I couldn't see any essential difference between this new > > > > implementation and the original one except that the former tries > > > > to use the library function - bsearch() to replace the original > > > > binary search algorithm implemented in TIPC itself. Therefore, I > > > > don't think the change will have a big impact on performance. > > > > > > > > If I miss something, please let me know. > > > > > > Comparison via a function pointer in bsearch is slower than direct > > > code without the function call overhead. > > > > > > > Right, but probably we can tolerate the slight sacrifice here. > > What part of "very time critical" have you verified and benchmarked as > inconsequential? > > Please post your results.
I agree with Joe here. This change does not simplify anything, it does not reduce the amount of code, plus that it introduce an unnecessary outline call in a place where we have every reason to let the compiler do its optimization job properly. ///jon
