From: Kirill A. Korinsky Subject: Re: sys/uvideo: avoid one bcopy when reads into mmaped memory To: tech@openbsd.org, mglocker@openbsd.org Date: Wed, 26 Feb 2025 23:51:34 +0100 On Wed, 26 Feb 2025 23:10:01 +0100, Kirill A. Korinsky wrote: > > tech@, > > Here a diff which removes one bcopy for each frame which is read from > webcamp into mmaped memory. > > Feedback? Ok? > Here the diff which is based on the latest version of uvideo. Index: sys/dev/usb/uvideo.c =================================================================== RCS file: /home/cvs/src/sys/dev/usb/uvideo.c,v diff -u -p -r1.246 uvideo.c --- sys/dev/usb/uvideo.c 26 Feb 2025 21:03:52 -0000 1.246 +++ sys/dev/usb/uvideo.c 26 Feb 2025 22:42:50 -0000 @@ -66,6 +66,7 @@ struct uvideo_softc { struct uvideo_frame_buffer sc_frame_buffer; struct uvideo_mmap sc_mmap[UVIDEO_MAX_BUFFERS]; + struct uvideo_mmap *sc_mmap_cur; uint8_t *sc_mmap_buffer; size_t sc_mmap_buffer_size; q_mmap sc_mmap_q; @@ -171,7 +172,8 @@ void uvideo_vs_decode_stream_header(str uint8_t *, int); void uvideo_vs_decode_stream_header_isight(struct uvideo_softc *, uint8_t *, int); -void uvideo_mmap_queue(struct uvideo_softc *, uint8_t *, int, int); +uint8_t * uvideo_mmap_buf(struct uvideo_softc *); +void uvideo_mmap_queue(struct uvideo_softc *, int); void uvideo_read(struct uvideo_softc *, uint8_t *, int); usbd_status uvideo_usb_control(struct uvideo_softc *, uint8_t, uint8_t, uint16_t, uint8_t *, size_t); @@ -2313,6 +2315,7 @@ uvideo_vs_decode_stream_header(struct uv struct uvideo_frame_buffer *fb = &sc->sc_frame_buffer; struct usb_video_stream_header *sh; int sample_len; + uint8_t *buf; if (frame_size < UVIDEO_SH_MIN_LEN) /* frame too small to contain a valid stream header */ @@ -2370,8 +2373,14 @@ uvideo_vs_decode_stream_header(struct uv sample_len = fb->buf_size - fb->offset; fb->error = 1; } - if (sample_len > 0) { - bcopy(frame + sh->bLength, fb->buf + fb->offset, sample_len); + + if (sc->sc_mmap_flag) + buf = uvideo_mmap_buf(sc); + else + buf = fb->buf; + + if (buf && sample_len > 0) { + bcopy(frame + sh->bLength, buf + fb->offset, sample_len); fb->offset += sample_len; } @@ -2394,7 +2403,7 @@ uvideo_vs_decode_stream_header(struct uv #endif if (sc->sc_mmap_flag) { /* mmap */ - uvideo_mmap_queue(sc, fb->buf, fb->offset, fb->error); + uvideo_mmap_queue(sc, fb->error); } else if (fb->error) { DPRINTF(1, "%s: %s: error frame, skipped!\n", DEVNAME(sc), __func__); @@ -2431,6 +2440,7 @@ uvideo_vs_decode_stream_header_isight(st { struct uvideo_frame_buffer *fb = &sc->sc_frame_buffer; int sample_len, header = 0; + uint8_t *buf; uint8_t magic[] = { 0x11, 0x22, 0x33, 0x44, 0xde, 0xad, 0xbe, 0xef, 0xde, 0xad, 0xfa, 0xce }; @@ -2448,27 +2458,35 @@ uvideo_vs_decode_stream_header_isight(st if (header) { if (sc->sc_mmap_flag) { /* mmap */ - uvideo_mmap_queue(sc, fb->buf, fb->offset, 0); + uvideo_mmap_queue(sc, 0); } else { /* read */ uvideo_read(sc, fb->buf, fb->offset); } fb->offset = 0; } else { + if (sc->sc_mmap_flag) + buf = uvideo_mmap_buf(sc); + else + buf = fb->buf; + /* save sample */ sample_len = frame_size; - if ((fb->offset + sample_len) <= fb->buf_size) { - bcopy(frame, fb->buf + fb->offset, sample_len); + if (buf && (fb->offset + sample_len) <= fb->buf_size) { + bcopy(frame, buf + fb->offset, sample_len); fb->offset += sample_len; } } } -void -uvideo_mmap_queue(struct uvideo_softc *sc, uint8_t *buf, int len, int err) +uint8_t * +uvideo_mmap_buf(struct uvideo_softc *sc) { int i; + if (sc->sc_mmap_cur) + return sc->sc_mmap_cur->buf; + if (sc->sc_mmap_count == 0 || sc->sc_mmap_buffer == NULL) panic("%s: mmap buffers not allocated", __func__); @@ -2480,32 +2498,47 @@ uvideo_mmap_queue(struct uvideo_softc *s if (i == sc->sc_mmap_count) { DPRINTF(1, "%s: %s: mmap queue is full!\n", DEVNAME(sc), __func__); - return; + return NULL; } - /* copy frame to mmap buffer and report length */ - bcopy(buf, sc->sc_mmap[i].buf, len); - sc->sc_mmap[i].v4l2_buf.bytesused = len; + sc->sc_mmap_cur = &sc->sc_mmap[i]; + sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_QUEUED; + + DPRINTF(2, "%s: %s: frame dequeued on index: %d\n", + DEVNAME(sc), __func__, i); + + return sc->sc_mmap_cur->buf; +} + +void +uvideo_mmap_queue(struct uvideo_softc *sc, int err) +{ + if (sc->sc_mmap_cur == NULL) + return; + + /* report length */ + sc->sc_mmap_cur->v4l2_buf.bytesused = sc->sc_frame_buffer.offset; /* timestamp it */ - getmicrouptime(&sc->sc_mmap[i].v4l2_buf.timestamp); - sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMESTAMP_MASK; - sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC; - sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_MASK; - sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_TSTAMP_SRC_EOF; - sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMECODE; + getmicrouptime(&sc->sc_mmap_cur->v4l2_buf.timestamp); + sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMESTAMP_MASK; + sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC; + sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_MASK; + sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_TSTAMP_SRC_EOF; + sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_TIMECODE; /* forward error bit */ - sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_ERROR; + sc->sc_mmap_cur->v4l2_buf.flags &= ~V4L2_BUF_FLAG_ERROR; if (err) - sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_ERROR; + sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_ERROR; /* queue it */ - sc->sc_mmap[i].v4l2_buf.flags |= V4L2_BUF_FLAG_DONE; - sc->sc_mmap[i].v4l2_buf.flags &= ~V4L2_BUF_FLAG_QUEUED; - SIMPLEQ_INSERT_TAIL(&sc->sc_mmap_q, &sc->sc_mmap[i], q_frames); - DPRINTF(2, "%s: %s: frame queued on index %d\n", - DEVNAME(sc), __func__, i); + sc->sc_mmap_cur->v4l2_buf.flags |= V4L2_BUF_FLAG_DONE; + SIMPLEQ_INSERT_TAIL(&sc->sc_mmap_q, sc->sc_mmap_cur, q_frames); + + sc->sc_mmap_cur = NULL; + + DPRINTF(2, "%s: %s: frame queued\n", DEVNAME(sc), __func__); wakeup(sc);