* Alan Stern | 2011-08-01 10:02:17 [-0400]: >> Using uncached memory has the benefit that reads/writes are performed >> directly to main memory but since you bypass the cache, every access >> goes across the bus. So uncached memory is probably a good if you need >> to access the memory just once or twice. > >That's exactly the problem. In uvcvideo, the memory _is_ accessed just >once. But even that once is slow enough to cause problems, according >to the original complaint. By once I meant only one location within that memory. >> Is it possible to align the buffers somehow differrently and avoid the >> memcpy in the first place? > >IIUC, there's no way to avoid copying the data since it has to >processed before getting sent to userspace. So it may be worth to try the dma api ops. >Alan Stern > Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
