diff options
| author | bde <bde@FreeBSD.org> | 2003-09-15 13:49:18 +0000 |
|---|---|---|
| committer | bde <bde@FreeBSD.org> | 2003-09-15 13:49:18 +0000 |
| commit | 286bde0c9de8e595ed2ec8e3ffa15cdc0f64b523 (patch) | |
| tree | b72677300b21060ebe57aa63dc51a5ee5f401849 | |
| parent | 7f14fd53128df22f4bc1cac494908f253582293c (diff) | |
| download | FreeBSD-src-286bde0c9de8e595ed2ec8e3ffa15cdc0f64b523.zip FreeBSD-src-286bde0c9de8e595ed2ec8e3ffa15cdc0f64b523.tar.gz | |
Quick fix for a pessimization in rev.1.194. An extra i/o instruction
was added to the fast path to support the COM_IIR_RXRDYBUG() case even
when that case is not configured. This increased the relative overhead
of sio input by almost 25% in the worst case and by 2-3% in the usual
case (usually only about 0.2% absolute per port at 115200 bps). The
quick fix is to significantly pessimize only the COM_IIR_RXRDYBUG()
case.
| -rw-r--r-- | sys/dev/sio/sio.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c index 0e42323..916f5dd 100644 --- a/sys/dev/sio/sio.c +++ b/sys/dev/sio/sio.c @@ -1770,8 +1770,13 @@ siointr1(com) u_char int_ctl; u_char int_ctl_new; - int_ctl = inb(com->intr_ctl_port); - int_ctl_new = int_ctl; + if (COM_IIR_TXRDYBUG(com->flags)) { + int_ctl = inb(com->intr_ctl_port); + int_ctl_new = int_ctl; + } else { + int_ctl = 0; + int_ctl_new = 0; + } while (!com->gone) { if (com->pps.ppsparam.mode & PPS_CAPTUREBOTH) { |
