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Comment out L4Cksum code from pcap tx thread

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We are not rewriting L4Cksum for ttag packets at the moment. See
comment in packetsequence.h

Commenting out this code doesn't seem to observably improve tx
performance though.

The latency code seems to reduce stream stats max tx performance
by around 3 to 5%. Recovering this may be done separately as part
of overall performance optimzation of Tx code.
This commit is contained in:
Srivats P 2023-05-08 15:28:19 +05:30
parent accc47fa34
commit f98c8af594
1 changed files with 6 additions and 0 deletions
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6
server/pcaptxthread.cpp
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@ -456,7 +456,9 @@ int PcapTxThread::sendQueueTransmit(pcap_t *p, PacketSequence *seq,
uchar *pkt = (uchar*)hdr + sizeof(*hdr);
int pktLen = hdr->caplen;
bool ttagPkt = false;
#if 0
quint16 origCksum = 0;
#endif
// Time for a T-Tag packet?
if (stats_->pkts == nextTtagPkt_) {
@ -466,6 +468,7 @@ int PcapTxThread::sendQueueTransmit(pcap_t *p, PacketSequence *seq,
*(pkt+pktLen-5) = SignProtocol::kTypeLenTtag;
*(pkt+pktLen-6) = ttagId_;
#if 0
// Recalc L4 checksum; use incremental checksum as per RFC 1624
// HC' = ~(~HC + ~m + m')
if (seq->ttagL4CksumOffset_) {
@ -489,6 +492,7 @@ int PcapTxThread::sendQueueTransmit(pcap_t *p, PacketSequence *seq,
// is present - we choose not to do this to avoid extra cost
*cksum = qToBigEndian(quint16(~newCksum));
}
#endif
ttagId_++;
nextTtagPkt_ += ttagDeltaMarkers_.at(ttagMarkerIndex_);
ttagMarkerIndex_++;
@ -524,11 +528,13 @@ int PcapTxThread::sendQueueTransmit(pcap_t *p, PacketSequence *seq,
if (ttagPkt) {
*(pkt+pktLen-5) = SignProtocol::kTypeLenTtagPlaceholder;
*(pkt+pktLen-6) = 0;
#if 0
if (seq->ttagL4CksumOffset_) {
quint16 *cksum = reinterpret_cast<quint16*>(
pkt + seq->ttagL4CksumOffset_);
*cksum = qToBigEndian(origCksum);
}
#endif
}
// Step to the next packet in the buffer