From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: Use of parallel init threads for slow devices start ups? Date: Mon, 19 Feb 2007 16:48:57 -0800 Message-ID: <20070220004857.GB9922@kroah.com> References: <3B6D69C3A9EBCA4BA5DA60D9130274295B9D66@dlee13.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <3B6D69C3A9EBCA4BA5DA60D9130274295B9D66@dlee13.ent.ti.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.osdl.org Errors-To: linux-pm-bounces@lists.osdl.org To: "Woodruff, Richard" Cc: "Reddy, Teerth" , pm list List-Id: linux-pm@vger.kernel.org On Mon, Feb 19, 2007 at 11:50:38AM -0600, Woodruff, Richard wrote: > Hi, > = > While doing some startup time profiling it is noticed we spend a lot of > time in the idle loop. As there is only one thread initializing devices > there is no one to schedule during device start ups. So for example an > external sensor might need a couple seconds to power up. > = > Does anyone want to give an opinion on forking off a parallel thread to > handle slower devices which are not dependent? I've added options to the kernel to do just this, and in the end, it wasn't really worth it. Yes, it does save some time for some machines, but the number of errors it added was quite large as most drivers and bus subsystems are not ready to handle such multi-threaded probing. But you can try it out yourself if you want, look at the patches in the previous few kernel releases that enable this functionality. thanks, greg k-h