From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olaf Hering Subject: Re: [PATCH 2 of 4] xenpaging: use wait queues Date: Fri, 2 Dec 2011 17:43:57 +0100 Message-ID: <20111202164357.GA29226@aepfle.de> References: <782967b2dc26ac23e527e33839e8336f.squirrel@webmail.lagarcavilla.org> <20111201184616.GA17010@aepfle.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Andres Lagar-Cavilla Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Fri, Dec 02, Andres Lagar-Cavilla wrote: > > The pager is in the process of writing the gfn to disk after successful > > nomination. Its next step is the eviction, which will now fail because > > the p2mt is not p2m_ram_paging_out anymore. It is already prepared for > > that failure. > > The previous MEM_EVENT_FLAG_EVICT_FAIL was not needed in the first > > place. > Yes it was! The biggest source of overhead is I/O. Tell the pager to stop > I/O early. Otherwise, you've done the paging out I/O pointlessly, to find > out only when you try to finalize the eviction. I'm not sure how to inform the pager, its most likely in the middle of write(). Since such an event is rare (in my testing at least) I wonder wether its worth to make it complicated? Olaf