From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] percpu-refcount: support synchronous switch to atomic mode. Date: Wed, 22 Mar 2017 11:00:29 -0400 Message-ID: <20170322150029.GA7532@htj.duckdns.org> References: <87o9wuaxm3.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <87o9wuaxm3.fsf@notabene.neil.brown.name> Sender: linux-kernel-owner@vger.kernel.org To: NeilBrown Cc: Christoph Lameter , linux-kernel@vger.kernel.org, Shaohua Li , Linux-RAID List-Id: linux-raid.ids On Wed, Mar 22, 2017 at 12:50:12PM +1100, NeilBrown wrote: > > percpu_ref_switch_to_atomic_sync() schedules the switch > to atomic mode, then waits for it to complete. > > Also export percpu_ref_switch_to_* so they can be used from modules. > > This will be used in md/raid to count the number of pending write > requests to an array. > We occasionally need to check if the count is zero, but most often > we don't care. > We always want updates to the counter to be fast, as in some cases > we count every 4K page. > > Signed-off-by: NeilBrown Acked-by: Tejun Heo Please feel free to route through other patches through md tree. If preferable, I can route it through percpu/for-4.12. Thanks. -- tejun