On 04/08/2011 05:40 PM, Marko Ristola wrote: > Avoid unnecessary DVB TS 188 sized packet copying from DMA buffer into stack. > Backtrack one 188 sized packet just after some garbage bytes when possible. > This obsoletes patch https://patchwork.kernel.org/patch/118147/ > > Signed-off-by: Marko Ristola marko.ristola@xxxxxxxxxxx Did you intentionally send a version that doesn't use likely()? Anyway, those optimizations can still be done in an incremental patch. Acked-by: Andreas Oberritter <obi@xxxxxxxxxxx> > diff --git a/drivers/media/dvb/dvb-core/dvb_demux.c b/drivers/media/dvb/dvb-core/dvb_demux.c > index 4a88a3e..faa3671 100644 > --- a/drivers/media/dvb/dvb-core/dvb_demux.c > +++ b/drivers/media/dvb/dvb-core/dvb_demux.c > @@ -478,97 +478,94 @@ void dvb_dmx_swfilter_packets(struct dvb_demux *demux, const u8 *buf, > > EXPORT_SYMBOL(dvb_dmx_swfilter_packets); > > -void dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf, size_t count) > +static inline int find_next_packet(const u8 *buf, int pos, size_t count, > + const int pktsize) > { > - int p = 0, i, j; > + int start = pos, lost; > > - spin_lock(&demux->lock); > - > - if (demux->tsbufp) { > - i = demux->tsbufp; > - j = 188 - i; > - if (count < j) { > - memcpy(&demux->tsbuf[i], buf, count); > - demux->tsbufp += count; > - goto bailout; > - } > - memcpy(&demux->tsbuf[i], buf, j); > - if (demux->tsbuf[0] == 0x47) > - dvb_dmx_swfilter_packet(demux, demux->tsbuf); > - demux->tsbufp = 0; > - p += j; > + while (pos < count) { > + if (buf[pos] == 0x47 || > + (pktsize == 204 && buf[pos] == 0xB8)) > + break; > + pos++; > } > > - while (p < count) { > - if (buf[p] == 0x47) { > - if (count - p >= 188) { > - dvb_dmx_swfilter_packet(demux, &buf[p]); > - p += 188; > - } else { > - i = count - p; > - memcpy(demux->tsbuf, &buf[p], i); > - demux->tsbufp = i; > - goto bailout; > - } > - } else > - p++; > + lost = pos - start; > + if (lost) { > + /* This garbage is part of a valid packet? */ > + int backtrack = pos - pktsize; > + if (backtrack >= 0 && (buf[backtrack] == 0x47 || > + (pktsize == 204 && buf[backtrack] == 0xB8))) > + return backtrack; > } > > -bailout: > - spin_unlock(&demux->lock); > + return pos; > } > > -EXPORT_SYMBOL(dvb_dmx_swfilter); > - > -void dvb_dmx_swfilter_204(struct dvb_demux *demux, const u8 *buf, size_t count) > +/* Filter all pktsize= 188 or 204 sized packets and skip garbage. */ > +static inline void _dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf, > + size_t count, const int pktsize) > { > int p = 0, i, j; > - u8 tmppack[188]; > + const u8 *q; > > spin_lock(&demux->lock); > > - if (demux->tsbufp) { > + if (demux->tsbufp) { /* tsbuf[0] is now 0x47. */ > i = demux->tsbufp; > - j = 204 - i; > + j = pktsize - i; > if (count < j) { > memcpy(&demux->tsbuf[i], buf, count); > demux->tsbufp += count; > goto bailout; > } > memcpy(&demux->tsbuf[i], buf, j); > - if ((demux->tsbuf[0] == 0x47) || (demux->tsbuf[0] == 0xB8)) { > - memcpy(tmppack, demux->tsbuf, 188); > - if (tmppack[0] == 0xB8) > - tmppack[0] = 0x47; > - dvb_dmx_swfilter_packet(demux, tmppack); > - } > + if (demux->tsbuf[0] == 0x47) /* double check */ > + dvb_dmx_swfilter_packet(demux, demux->tsbuf); > demux->tsbufp = 0; > p += j; > } > > - while (p < count) { > - if ((buf[p] == 0x47) || (buf[p] == 0xB8)) { > - if (count - p >= 204) { > - memcpy(tmppack, &buf[p], 188); > - if (tmppack[0] == 0xB8) > - tmppack[0] = 0x47; > - dvb_dmx_swfilter_packet(demux, tmppack); > - p += 204; > - } else { > - i = count - p; > - memcpy(demux->tsbuf, &buf[p], i); > - demux->tsbufp = i; > - goto bailout; > - } > - } else { > - p++; > + while (1) { > + p = find_next_packet(buf, p, count, pktsize); > + if (p >= count) > + break; > + if (count - p < pktsize) > + break; > + > + q = &buf[p]; > + > + if (pktsize == 204 && (*q == 0xB8)) { > + memcpy(demux->tsbuf, q, 188); > + demux->tsbuf[0] = 0x47; > + q = demux->tsbuf; > } > + dvb_dmx_swfilter_packet(demux, q); > + p += pktsize; > + } > + > + i = count - p; > + if (i) { > + memcpy(demux->tsbuf, &buf[p], i); > + demux->tsbufp = i; > + if (pktsize == 204 && demux->tsbuf[0] == 0xB8) > + demux->tsbuf[0] = 0x47; > } > > bailout: > spin_unlock(&demux->lock); > } > > +void dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf, size_t count) > +{ > + _dvb_dmx_swfilter(demux, buf, count, 188); > +} > +EXPORT_SYMBOL(dvb_dmx_swfilter); > + > +void dvb_dmx_swfilter_204(struct dvb_demux *demux, const u8 *buf, size_t count) > +{ > + _dvb_dmx_swfilter(demux, buf, count, 204); > +} > EXPORT_SYMBOL(dvb_dmx_swfilter_204); > > static struct dvb_demux_filter *dvb_dmx_filter_alloc(struct dvb_demux *demux) > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
