Hi Christoph, On 2019/11/4 23:25, Christoph Hellwig wrote: > On Mon, Nov 04, 2019 at 07:29:40PM +0800, Shaokun Zhang wrote: >> From: Yang Guo <guoyang2@xxxxxxxxxx> >> >> percpu_counter_compare will be called by xfs_mod_icount/ifree to check >> whether the counter less than 0 and it is a expensive function. >> let's check it only when delta < 0, it will be good for xfs's performance. > > How much overhead do you see? In the end the compare is just a debug Thanks your reply, sorry for my not clear description. __percpu_counter_compare itself is not expensive, but __percpu_counter_sum called by __percpu_counter_compare is high load, I will list it in next thread. > check, so if it actually shows up we should remove it entirely. > I'm not sure about it, so I check the delta to do less modification. Thanks, Shaokun >
