Re: [Linux-cachefs] [External] Re: [PATCH V4 4/5] cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode

Wed, 29 Mar 2023 01:09:34 -0700 


在 2023/3/28 22:19, David Howells 写道:

Jia Zhu <[email protected]> wrote:


+               if (!xa_empty(xa)) {
+                       xa_lock(xa);
+                       xa_for_each_marked(xa, index, req, CACHEFILES_REQ_NEW) {
+                               if 
(!cachefiles_ondemand_is_reopening_read(req)) {
+                                       mask |= EPOLLIN;
+                                       break;
+                               }
+                       }
+                       xa_unlock(xa);
+               }


I wonder if there's a more efficient way to do this.  I guess it depends on
how many reqs you expect to get in a queue.  It might be worth taking the
rcu_read_lock before calling xa_lock() and holding it over the whole loop.


Thanks for the advice, will use rcu_read_lock（unlock） to replace it.

David



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