On Mon, Mar 21, 2022 at 11:18:05PM +0800, JeffleXu wrote: > >> Besides, IMHO read-write lock shall be more performance friendly, since > >> most cases are the read side. > > > > That's almost never true. rwlocks are usually a bad idea because you > > still have to bounce the cacheline, so you replace lock contention > > (which you can see) with cacheline contention (which is harder to > > measure). And then you have questions about reader/writer fairness > > (should new readers queue behind a writer if there's one waiting, or > > should a steady stream of readers be able to hold a writer off > > indefinitely?) > > Interesting, I didn't notice it before. Thanks for explaining it. No problem. It's hard to notice. > BTW what I want is just > > ``` > PROCESS 1 PROCESS 2 > ========= ========= > #lock #lock > set DEAD state if (not DEAD) > flush xarray enqueue into xarray > #unlock #unlock > ``` > > I think it is a generic paradigm. So it seems that the spinlock inside > xarray is already adequate for this job? Absolutely; just use xa_lock() to protect both setting & testing the flag.
