From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Thu, 18 Feb 2010 15:54:56 +0000 Subject: Re: [PATCH 3/10] udlfb: pre-allocated urb list helpers Message-Id: <20100218155456.GC21785@kroah.com> List-Id: References: <1266245155.4353.3298.camel@bernie-aspireone> In-Reply-To: <1266245155.4353.3298.camel@bernie-aspireone> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-fbdev@vger.kernel.org On Mon, Feb 15, 2010 at 06:45:55AM -0800, Bernie Thompson wrote: > Add functions to pre-allocate and free usb bulk urbs for core render path. > > Udlfb currently allocates a single urb, guarded by a mutex, that is a key > bottleneck. Because udlfb sends so much data, preallocation is most efficient. I'm not going to reject this patch, but are you sure about this being needed? The code path for creating a new urb is very tiny, just a memory allocation. Is that really noticable in any benchmarks or cpu usage that you have found? curious, greg k-h