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authorOndrej Zajicek <santiago@crfreenet.org>2009-10-11 18:56:16 +0200
committerOndrej Zajicek <santiago@crfreenet.org>2009-10-11 18:56:16 +0200
commitea89da381fc682155e7d08d6ad3d4ac8aa5fe115 (patch)
tree169955732d5886614af061e9472473b01fb8904c /sysdep/unix
parent7ea5b00f42bd3d1fdafb0be349e3ebbcdf3ea466 (diff)
downloadbird-ea89da381fc682155e7d08d6ad3d4ac8aa5fe115.tar
bird-ea89da381fc682155e7d08d6ad3d4ac8aa5fe115.zip
Workaround for stupid callback scheduler.
There is no reak callback scheduler and previous behavior causes bad things during hard congestion (like BGP hold timeouts). Smart callback scheduler is still missing, but main loop was changed such that it first processes all tx callbacks (which are fast enough) (but max 4* per socket) + rx callbacks for CLI, and in the second phase it processes one rx callback per socket up to four sockets (as rx callback can be slow when there are too many protocols, because route redistribution is done synchronously inside rx callback). If there is event callback ready, second phase is skipped in 90% of iterations (to speed up CLI during congestion).
Diffstat (limited to 'sysdep/unix')
-rw-r--r--sysdep/unix/io.c77
1 files changed, 72 insertions, 5 deletions
diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index 99d3393..330aea4 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -30,12 +30,17 @@
#include "lib/unix.h"
#include "lib/sysio.h"
-/* Maximum number of calls of rx/tx handler for one socket in one
+/* Maximum number of calls of tx handler for one socket in one
* select iteration. Should be small enough to not monopolize CPU by
* one protocol instance.
*/
#define MAX_STEPS 4
+/* Maximum number of calls of rx handler for all sockets in one select
+ iteration. RX callbacks are often much more costly so we limit
+ this to gen small latencies */
+#define MAX_RX_STEPS 4
+
/*
* Tracked Files
*/
@@ -493,6 +498,7 @@ tm_format_reltime(char *x, bird_clock_t t)
static list sock_list;
static struct birdsock *current_sock;
+static struct birdsock *stored_sock;
static int sock_recalc_fdsets_p;
static inline sock *
@@ -541,6 +547,8 @@ sk_free(resource *r)
close(s->fd);
if (s == current_sock)
current_sock = sk_next(s);
+ if (s == stored_sock)
+ stored_sock = sk_next(s);
rem_node(&s->n);
sock_recalc_fdsets_p = 1;
}
@@ -1071,6 +1079,29 @@ sk_maybe_write(sock *s)
}
}
+int
+sk_rx_ready(sock *s)
+{
+ fd_set rd, wr;
+ struct timeval timo;
+ int rv;
+
+ FD_ZERO(&rd);
+ FD_ZERO(&wr);
+ FD_SET(s->fd, &rd);
+
+ timo.tv_sec = 0;
+ timo.tv_usec = 0;
+
+ redo:
+ rv = select(s->fd+1, &rd, &wr, NULL, &timo);
+
+ if ((rv < 0) && (errno == EINTR || errno == EAGAIN))
+ goto redo;
+
+ return rv;
+}
+
/**
* sk_send - send data to a socket
* @s: socket
@@ -1239,6 +1270,9 @@ io_init(void)
srandom((int) now_real);
}
+static int short_loops = 0;
+#define SHORT_LOOP_MAX 10
+
void
io_loop(void)
{
@@ -1317,8 +1351,8 @@ io_loop(void)
}
/* And finally enter select() to find active sockets */
-
hi = select(hi+1, &rd, &wr, NULL, &timo);
+
if (hi < 0)
{
if (errno == EINTR || errno == EAGAIN)
@@ -1327,13 +1361,17 @@ io_loop(void)
}
if (hi)
{
- current_sock = SKIP_BACK(sock, n, HEAD(sock_list)); /* guaranteed to be non-empty */
+ /* guaranteed to be non-empty */
+ current_sock = SKIP_BACK(sock, n, HEAD(sock_list));
+
while (current_sock)
{
sock *s = current_sock;
int e;
- int steps = MAX_STEPS;
- if (FD_ISSET(s->fd, &rd) && s->rx_hook)
+ int steps;
+
+ steps = MAX_STEPS;
+ if ((s->type >= SK_MAGIC) && FD_ISSET(s->fd, &rd) && s->rx_hook)
do
{
steps--;
@@ -1356,6 +1394,35 @@ io_loop(void)
current_sock = sk_next(s);
next: ;
}
+
+ short_loops++;
+ if (events && (short_loops < SHORT_LOOP_MAX))
+ continue;
+ short_loops = 0;
+
+ int count = 0;
+ current_sock = stored_sock;
+ if (current_sock == NULL)
+ current_sock = SKIP_BACK(sock, n, HEAD(sock_list));
+
+ while (current_sock && count < MAX_RX_STEPS)
+ {
+ sock *s = current_sock;
+ int e;
+ int steps;
+
+ if ((s->type < SK_MAGIC) && FD_ISSET(s->fd, &rd) && s->rx_hook)
+ {
+ count++;
+ e = sk_read(s);
+ if (s != current_sock)
+ goto next2;
+ }
+ current_sock = sk_next(s);
+ next2: ;
+ }
+
+ stored_sock = current_sock;
}
}
}