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tcp: Rework timers to use timerfd instead of periodic bitmap scan

Browse source 
With a lot of concurrent connections, the bitmap scan approach is
not really sustainable.

Switch to per-connection timerfd timers, set based on events and on
two new flags, ACK_FROM_TAP_DUE and ACK_TO_TAP_DUE. Timers are added
to the common epoll list, and implement the existing timeouts.

While at it, drop the CONN_ prefix from flag names, otherwise they
get quite long, and fix the logic to decide if a connection has a
local, possibly unreachable endpoint: we shouldn't go through the
rest of tcp_conn_from_tap() if we reset the connection due to a
successful bind(2), and we'll get EACCES if the port number is low.

Suggested by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2022-03-18 12:18:19 +01:00
parent 3eb19cfd8a
commit be5bbb9b06
5 changed files with 288 additions and 241 deletions

12
passt.c
View file

@ -119,12 +119,12 @@ static void post_handler(struct ctx *c, struct timespec *now)
#define CALL_PROTO_HANDLER(c, now, lc, uc) \
do { \
extern void \
lc ## _defer_handler (struct ctx *, struct timespec *) \
lc ## _defer_handler (struct ctx *c) \
__attribute__ ((weak)); \
\
if (!c->no_ ## lc) { \
if (lc ## _defer_handler) \
lc ## _defer_handler(c, now); \
lc ## _defer_handler(c); \
\
if (timespec_diff_ms((now), &c->lc.timer_run) \
>= uc ## _TIMER_INTERVAL) { \
@ -134,8 +134,11 @@ static void post_handler(struct ctx *c, struct timespec *now)
} \
} while (0)
/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
CALL_PROTO_HANDLER(c, now, tcp, TCP);
/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
CALL_PROTO_HANDLER(c, now, udp, UDP);
/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
CALL_PROTO_HANDLER(c, now, icmp, ICMP);
#undef CALL_PROTO_HANDLER
@ -380,8 +383,8 @@ int main(int argc, char **argv)
clock_gettime(CLOCK_MONOTONIC, &now);
if ((!c.no_udp && udp_sock_init(&c, &now)) ||
(!c.no_tcp && tcp_sock_init(&c, &now)))
if ((!c.no_udp && udp_sock_init(&c)) ||
(!c.no_tcp && tcp_sock_init(&c)))
exit(EXIT_FAILURE);
proto_update_l2_buf(c.mac_guest, c.mac, &c.addr4);
@ -425,6 +428,7 @@ int main(int argc, char **argv)
timer_init(&c, &now);
loop:
/* NOLINTNEXTLINE(bugprone-branch-clone): intervals can be the same */
nfds = epoll_wait(c.epollfd, events, EPOLL_EVENTS, TIMER_INTERVAL);
if (nfds == -1 && errno != EINTR) {
perror("epoll_wait");