Re: [PATCH] tmpfs: use ida to get inode number

[Al Viro]

On Fri, Nov 22, 2019 at 06:33:25PM -0800, Matthew Wilcox wrote:
> On Sat, Nov 23, 2019 at 10:16:39AM +0800, zhengbin (A) wrote:
> > By the way, percpu IDA is for reducing performance impact? This patch has 2.16%
> > performance degradation(Use perf to get the cost of ida_alloc_range)
> 
> 2.16% degradation in your tests ... I bet Eric didn't make it so complex
> for only 2% performance impact.  Unfortunately, he didn't give any
> numbers in his patch submission, but it's going to be a bigger problem
> on multi-socket machines than on a laptop.

It could also be that socket(2) is called (on real loads) just a bit
more often than open(2) in a benchmark that tests file creation...