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Reduce mutex use in LinuxEthernetTap. Try to squeeze a bit more powah out of it.

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Adam Ierymenko 2020-11-18 12:50:34 -05:00
parent b152f9e1d3
commit 7cbbc38b89
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GPG key ID: C8877CF2D7A5D7F3
1 changed files with 14 additions and 5 deletions
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19
osdep/LinuxEthernetTap.cpp
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@ -188,6 +188,7 @@ LinuxEthernetTap::LinuxEthernetTap(
fd_set readfds,nullfds; fd_set readfds,nullfds;
int n,nfds,r; int n,nfds,r;
void *buf = nullptr; void *buf = nullptr;
std::vector buffers;
{ {
struct ifreq ifr; struct ifreq ifr;
@ -252,14 +253,20 @@ LinuxEthernetTap::LinuxEthernetTap(
if (FD_ISSET(_fd,&readfds)) { if (FD_ISSET(_fd,&readfds)) {
for(;;) { // read until there are no more packets, then return to outer select() loop for(;;) { // read until there are no more packets, then return to outer select() loop
if (!buf) { if (!buf) {
std::lock_guard<std::mutex> l(_buffers_l); // To reduce use of the mutex, we keep a local buffer vector and
if (_buffers.empty()) { // swap (which is a pointer swap) with the global one when it's
// empty. This retrieves a batch of buffers to use.
if (buffers.empty()) {
std::lock_guard<std::mutex> l(_buffers_l);
buffers.swap(_buffers);
}
if (buffers.empty()) {
buf = malloc(ZT_TAP_BUF_SIZE); buf = malloc(ZT_TAP_BUF_SIZE);
if (!buf) if (!buf)
break; break;
} else { } else {
buf = _buffers.back(); buf = buffers.back();
_buffers.pop_back(); buffers.pop_back();
} }
} }
@ -302,7 +309,9 @@ LinuxEthernetTap::LinuxEthernetTap(
_handler(_arg, nullptr, _nwid, from, to, etherType, 0, (const void *)(b + 14),(unsigned int)(qi.second - 14)); _handler(_arg, nullptr, _nwid, from, to, etherType, 0, (const void *)(b + 14),(unsigned int)(qi.second - 14));
{ {
std::lock_guard<std::mutex> l(_buffers_l); std::lock_guard<std::mutex> l(_buffers_l);
_buffers.push_back(qi.first); if (_buffers.size() < 128)
_buffers.push_back(qi.first);
else free(qi.first);
} }
} else break; } else break;
} }