From b8c6bcee1dbc1aadcd67af998e414e73fa166a7d Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Thu, 4 Sep 2008 07:30:19 +0200 Subject: dccp: Reduce noise in output and convert to ktime_t This fixes the problem that dccp_probe output can grow quite large without apparent benefit (many identical data points), creating huge files (up to over one Gigabyte for a few minutes' test run) which are very hard to post-process (in one instance it got so bad that gnuplot ate up all memory plus swap). The cause for the problem is that the kprobe is inserted into dccp_sendmsg(), which can be called in a polling-mode (whenever the TX queue is full due to congestion-control issues, EAGAIN is returned). This creates many very similar data points, i.e. the increase of processing time does not increase the quality/information of the probe output. The fix is to attach the probe to a different function -- write_xmit was chosen since it gets called continually (both via userspace and timer); an input-path function would stop sampling as soon as the other end stops sending feedback. For comparison the output file sizes for the same 20 second test run over a lossy link: * before / without patch: 118 Megabytes * after / with patch: 1.2 Megabytes and there was much less noise in the output. To allow backward compatibility with scripts that people use, the now-unused `size' field in the output has been replaced with the CCID identifier. This also serves for future compatibility - support for CCID2 is work in progress (depends on the still unfinished SRTT/RTTVAR updates). While at it, the update to ktime_t was also performed. Signed-off-by: Gerrit Renker Acked-by: Ian McDonald --- net/dccp/probe.c | 66 +++++++++++++++++++++----------------------------------- 1 file changed, 25 insertions(+), 41 deletions(-) (limited to 'net/dccp') diff --git a/net/dccp/probe.c b/net/dccp/probe.c index a87fd4fc1b3d..eaa59d82ab0f 100644 --- a/net/dccp/probe.c +++ b/net/dccp/probe.c @@ -46,70 +46,54 @@ static struct { struct kfifo *fifo; spinlock_t lock; wait_queue_head_t wait; - struct timespec tstart; + ktime_t start; } dccpw; -static void printl(const char *fmt, ...) -{ - va_list args; - int len; - struct timespec now; - char tbuf[256]; - - va_start(args, fmt); - getnstimeofday(&now); - - now = timespec_sub(now, dccpw.tstart); - - len = sprintf(tbuf, "%lu.%06lu ", - (unsigned long) now.tv_sec, - (unsigned long) now.tv_nsec / NSEC_PER_USEC); - len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args); - va_end(args); - - kfifo_put(dccpw.fifo, tbuf, len); - wake_up(&dccpw.wait); -} - -static int jdccp_sendmsg(struct kiocb *iocb, struct sock *sk, - struct msghdr *msg, size_t size) +static void jdccp_write_xmit(struct sock *sk) { const struct inet_sock *inet = inet_sk(sk); struct ccid3_hc_tx_sock *hctx = NULL; + struct timespec tv; + char buf[256]; + int len, ccid = ccid_get_current_tx_ccid(dccp_sk(sk)); - if (ccid_get_current_tx_ccid(dccp_sk(sk)) == DCCPC_CCID3) + if (ccid == DCCPC_CCID3) hctx = ccid3_hc_tx_sk(sk); - if (port == 0 || ntohs(inet->dport) == port || - ntohs(inet->sport) == port) { - if (hctx) - printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %d %d %d %u " - "%llu %llu %d\n", + if (!port || ntohs(inet->dport) == port || ntohs(inet->sport) == port) { + + tv = ktime_to_timespec(ktime_sub(ktime_get(), dccpw.start)); + len = sprintf(buf, "%lu.%09lu %d.%d.%d.%d:%u %d.%d.%d.%d:%u %d", + (unsigned long)tv.tv_sec, + (unsigned long)tv.tv_nsec, NIPQUAD(inet->saddr), ntohs(inet->sport), - NIPQUAD(inet->daddr), ntohs(inet->dport), size, + NIPQUAD(inet->daddr), ntohs(inet->dport), ccid); + + if (hctx) + len += sprintf(buf + len, " %d %d %d %u %u %u %d", hctx->s, hctx->rtt, hctx->p, hctx->x_calc, - hctx->x_recv >> 6, hctx->x >> 6, hctx->t_ipi); - else - printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d\n", - NIPQUAD(inet->saddr), ntohs(inet->sport), - NIPQUAD(inet->daddr), ntohs(inet->dport), size); + (unsigned)(hctx->x_recv >> 6), + (unsigned)(hctx->x >> 6), hctx->t_ipi); + + len += sprintf(buf + len, "\n"); + kfifo_put(dccpw.fifo, buf, len); + wake_up(&dccpw.wait); } jprobe_return(); - return 0; } static struct jprobe dccp_send_probe = { .kp = { - .symbol_name = "dccp_sendmsg", + .symbol_name = "dccp_write_xmit", }, - .entry = jdccp_sendmsg, + .entry = jdccp_write_xmit, }; static int dccpprobe_open(struct inode *inode, struct file *file) { kfifo_reset(dccpw.fifo); - getnstimeofday(&dccpw.tstart); + dccpw.start = ktime_get(); return 0; } -- cgit v1.2.3-59-g8ed1b