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Change WSDISPLAYBURST from OBUFSIZ-1 to OBUFSIZ*4, for a ~15x 

improvement in the "cat /usr/share/misc/termcap" benchmark on 486/75

ttwrite queues data for us in OBUFSIZ chunks.  If we only consume
OBUFSIZ-1 bytes per call to wsdisplaystart(), we're *guaranteed* to
fall behind when given maximum-sized reads (which will defer
processing the leftovers until ttrstrt gets called, after a timeout)

Note that OBUFSIZ*4 may be overkill; OBUFSIZ*3 may be sufficient to
get maximal performance; OBUFSIZ*2 resulted in only about a 2.5x
performance improvement, but it's 2am and I've done enough tweaking
for the night.
This commit is contained in:
sommerfe 1999-02-08 07:05:51 +00:00
parent 358b69935b
commit 95ee03319d
1 changed files with 3 additions and 3 deletions
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6
sys/dev/wscons/wsdisplay.c
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@ -1,4 +1,4 @@
/* $NetBSD: wsdisplay.c,v 1.18 1999/01/26 14:22:14 drochner Exp $ */
/* $NetBSD: wsdisplay.c,v 1.19 1999/02/08 07:05:51 sommerfe Exp $ */
/*
* Copyright (c) 1996, 1997 Christopher G. Demetriou. All rights reserved.
@ -33,7 +33,7 @@
static const char _copyright[] __attribute__ ((unused)) =
"Copyright (c) 1996, 1997 Christopher G. Demetriou. All rights reserved.";
static const char _rcsid[] __attribute__ ((unused)) =
"$NetBSD: wsdisplay.c,v 1.18 1999/01/26 14:22:14 drochner Exp $";
"$NetBSD: wsdisplay.c,v 1.19 1999/02/08 07:05:51 sommerfe Exp $";
#include <sys/param.h>
#include <sys/conf.h>
@ -174,7 +174,7 @@ static int wsdisplayparam __P((struct tty *, struct termios *));
#define WSDISPLAYSCREEN(dev) (minor(dev) & 0xff)
#define ISWSDISPLAYCTL(dev) (WSDISPLAYSCREEN(dev) == 255)
#define WSDISPLAYMINOR(unit, screen) (((unit) << 8) | (screen))
#define WSDISPLAYBURST (OBUFSIZ - 1)
#define WSDISPLAYBURST OBUFSIZ*4
#define WSSCREEN_HAS_EMULATOR(scr) ((scr)->scr_dconf->wsemul != NULL)
#define WSSCREEN_HAS_TTY(scr) ((scr)->scr_tty != NULL)