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X-Bullshit: overflow-preventing responsive deep-learning hypervisor XMPP dependency map/reduce-oriented GPU framework 
Subject: [9front] iounit: bump it across the board
Reply-To: 9front@9front.org
Precedence: bulk

DO NOT RUN THIS UNTIL YOU HAVE APPLIED THE CWFS PATCH. CWFS WILL HANG
UP ON YOU WITHOUT THE PATCH FROM THE EMAIL TITLED

	cwfs: fix iounit negotiation

This patch bumps up the iounit in the kernel to 32k, and
introduces the IOUNIT constant to take advantage of it.

This also changes some of userspace to increase buffer
sizes, so that we can take advantage of the larger reads.

Things to double check for:

	- libthread programs have limited stack sizes,
	  and increasing the size of the buffer may
	  blow the stack in some of these programs.

	- I may have misunderstood how buffer sizes
	  are used, and may have increased constants
	  that I shouldn't have.

	- General bugs and typos.

	- Bugs that changing the io unit tickles.

Note that when mounting 9p over TLS, the iounit will be
restricted to the iounit of the underlying transport,
in this case 16k. That may get addressed in a separate
patch.

diff 73cfaf9d694f927adf89c44e0cc7ad25df15bbdf uncommitted
--- a/sys/include/ape/bio.h
+++ b/sys/include/ape/bio.h
@@ -14,7 +14,7 @@
 
 enum
 {
-	Bsize		= 8*1024,
+	Bsize		= 32*1024,
 	Bungetsize	= UTFmax+1,	/* space for ungetc */
 	Bmagic		= 0x314159,
 	Beof		= -1,
--- a/sys/include/bio.h
+++ b/sys/include/bio.h
@@ -6,7 +6,7 @@
 
 enum
 {
-	Bsize		= 8*1024,
+	Bsize		= IOUNIT,
 	Bungetsize	= UTFmax+1,	/* space for ungetc */
 	Bmagic		= 0x314159,
 	Beof		= -1,
--- a/sys/include/libc.h
+++ b/sys/include/libc.h
@@ -567,6 +567,7 @@
 #define	STATMAX	65535U	/* max length of machine-independent stat structure */
 #define	DIRMAX	(sizeof(Dir)+STATMAX)	/* max length of Dir structure */
 #define	ERRMAX	128	/* max length of error string */
+#define IOUNIT	32768U	/* reasonable buffer size */
 
 #define	MORDER	0x0003	/* mask for bits defining order of mounting */
 #define	MREPL	0x0000	/* mount replaces object */
--- a/sys/src/9/port/devmnt.c
+++ b/sys/src/9/port/devmnt.c
@@ -16,7 +16,7 @@
  * connection.
  */
 
-#define MAXRPC (IOHDRSZ+8192)
+#define MAXRPC	(IOHDRSZ+32*1024)
 
 struct Mntrpc
 {
@@ -146,7 +146,7 @@
 	f.tag = NOTAG;
 	f.msize = msize;
 	f.version = v;
-	msg = malloc(8192+IOHDRSZ);
+	msg = malloc(MAXRPC);
 	if(msg == nil)
 		exhausted("version memory");
 	if(waserror()){
@@ -153,7 +153,7 @@
 		free(msg);
 		nexterror();
 	}
-	k = convS2M(&f, msg, 8192+IOHDRSZ);
+	k = convS2M(&f, msg, MAXRPC);
 	if(k == 0)
 		error("bad fversion conversion on send");
 
@@ -171,8 +171,8 @@
 	}
 
 	/* message sent; receive and decode reply */
-	for(k = 0; k < BIT32SZ || (k < GBIT32(msg) && k < 8192+IOHDRSZ); k += l){
-		l = devtab[c->type]->read(c, msg+k, 8192+IOHDRSZ-k, c->offset);
+	for(k = 0; k < BIT32SZ || (k < GBIT32(msg) && k < MAXRPC); k += l){
+		l = devtab[c->type]->read(c, msg+k, MAXRPC-k, c->offset);
 		if(l <= 0)
 			error("EOF receiving fversion reply");
 		lock(c);
--- a/sys/src/cmd/1a/a.h
+++ b/sys/src/cmd/1a/a.h
@@ -15,7 +15,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		500
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -52,7 +51,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/1l/l.h
+++ b/sys/src/cmd/1l/l.h
@@ -114,7 +114,6 @@
 	NHUNK		= 100000,
 	MINSIZ		= 4,
 	STRINGSZ	= 200,
-	MAXIO		= 8192,
 	MAXHIST		= 20,				/* limit of path elements for history symbols */
 	A6OFFSET 	= 32766,
 };
@@ -123,8 +122,8 @@
 {
 	struct
 	{
-		char	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		char	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/1l/obj.c
+++ b/sys/src/cmd/1l/obj.c
@@ -657,7 +657,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/2a/a.h
+++ b/sys/src/cmd/2a/a.h
@@ -15,7 +15,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		500
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -52,7 +51,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/2l/l.h
+++ b/sys/src/cmd/2l/l.h
@@ -116,7 +116,6 @@
 	NHUNK		= 100000,
 	MINSIZ		= 4,
 	STRINGSZ	= 200,
-	MAXIO		= 8192,
 	MAXHIST		= 20,				/* limit of path elements for history symbols */
 	A6OFFSET 	= 32766
 };
@@ -125,8 +124,8 @@
 {
 	struct
 	{
-		char	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		char	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/2l/obj.c
+++ b/sys/src/cmd/2l/obj.c
@@ -672,7 +672,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/5l/l.h
+++ b/sys/src/cmd/5l/l.h
@@ -197,7 +197,6 @@
 	NHUNK		= 100000,
 	MINSIZ		= 64,
 	NENT		= 100,
-	MAXIO		= 8192,
 	MAXHIST		= 20,	/* limit of path elements for history symbols */
 
 	Roffset	= 22,		/* no. bits for offset in relocation address */
@@ -208,8 +207,8 @@
 {
 	struct
 	{
-		uchar	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		uchar	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/5l/obj.c
+++ b/sys/src/cmd/5l/obj.c
@@ -682,7 +682,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/6a/a.h
+++ b/sys/src/cmd/6a/a.h
@@ -14,7 +14,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		500
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -51,7 +50,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/6l/l.h
+++ b/sys/src/cmd/6l/l.h
@@ -118,7 +118,6 @@
 	MINSIZ		= 8,
 	STRINGSZ	= 200,
 	MINLC		= 1,
-	MAXIO		= 8192,
 	MAXHIST		= 20,				/* limit of path elements for history symbols */
 
 	Yxxx		= 0,
@@ -225,8 +224,8 @@
 {
 	struct
 	{
-		char	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		char	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/6l/obj.c
+++ b/sys/src/cmd/6l/obj.c
@@ -728,7 +728,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/7a/a.h
+++ b/sys/src/cmd/7a/a.h
@@ -17,7 +17,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		8192
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -48,7 +47,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/7l/l.h
+++ b/sys/src/cmd/7l/l.h
@@ -238,7 +238,6 @@
 	STRINGSZ	= 200,
 	NHASH		= 10007,
 	NHUNK		= 100000,
-	MAXIO		= 8192,
 	MAXHIST		= 20,	/* limit of path elements for history symbols */
 };
 
@@ -246,8 +245,8 @@
 {
 	struct
 	{
-		uchar	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		uchar	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/7l/obj.c
+++ b/sys/src/cmd/7l/obj.c
@@ -575,7 +575,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/8a/a.h
+++ b/sys/src/cmd/8a/a.h
@@ -14,7 +14,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		500
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -51,7 +50,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/8l/l.h
+++ b/sys/src/cmd/8l/l.h
@@ -110,7 +110,6 @@
 	MINSIZ		= 4,
 	STRINGSZ	= 200,
 	MINLC		= 1,
-	MAXIO		= 8192,
 	MAXHIST		= 20,				/* limit of path elements for history symbols */
 
 	Yxxx		= 0,
@@ -199,8 +198,8 @@
 {
 	struct
 	{
-		char	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		char	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/8l/obj.c
+++ b/sys/src/cmd/8l/obj.c
@@ -716,7 +716,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/ar.c
+++ b/sys/src/cmd/ar.c
@@ -1087,7 +1087,7 @@
 {
 	Armember *bp;
 	int i;
-	char buf[8192];
+	char buf[IOUNIT];
 
 	if (ap->paged) {		/* copy from disk */
 		seek(ap->fd, 0, 0);
--- a/sys/src/cmd/audio/mp3enc/mpglib_interface.c
+++ b/sys/src/cmd/audio/mp3enc/mpglib_interface.c
@@ -47,7 +47,7 @@
         { 0, 384, 1152, 1152 }, /* MPEG-1     */
         { 0, 384, 1152,  576 }  /* MPEG-2(.5) */
     };
-    static char        out  [8192];
+    static char        out  [IOUNIT];
     signed short int*  p = (signed short int*) out;
     int                processed_bytes;
     int                processed_samples;  // processed samples per channel
--- a/sys/src/cmd/aux/consolefs.c
+++ b/sys/src/cmd/aux/consolefs.c
@@ -162,7 +162,7 @@
 char *consoledb = "/lib/ndb/consoledb";
 char *mntpt = "/mnt/consoles";
 
-int messagesize = 8192+IOHDRSZ;
+int messagesize = IOUNIT+IOHDRSZ;
 
 void
 fatal(char *fmt, ...)
@@ -760,8 +760,8 @@
 		return;
 	}
 	messagesize = r->f.msize;
-	if(messagesize > 8192+IOHDRSZ)
-		messagesize = 8192+IOHDRSZ;
+	if(messagesize > IOUNIT+IOHDRSZ)
+		messagesize = IOUNIT+IOHDRSZ;
 	r->f.msize = messagesize;
 	if(strncmp(r->f.version, "9P", 2) != 0)
 		r->f.version = "unknown";
--- a/sys/src/cmd/bzip2/bunzip2.c
+++ b/sys/src/cmd/bzip2/bunzip2.c
@@ -125,8 +125,8 @@
 bunzip(int ofd, char *ofile, Biobuf *bin)
 {
 	int e, n, done, onemore;
-	char buf[8192];
-	char obuf[8192];
+	char buf[IOUNIT];
+	char obuf[IOUNIT];
 	Biobuf bout;
 	bz_stream strm;
 
--- a/sys/src/cmd/bzip2/bzip2.c
+++ b/sys/src/cmd/bzip2/bzip2.c
@@ -132,8 +132,8 @@
 bzip(char *file, long mtime, int ifd, Biobuf *bout)
 {
 	int e, n, done, onemore;
-	char buf[8192];
-	char obuf[8192];
+	char buf[IOUNIT];
+	char obuf[IOUNIT];
 	Biobuf bin;
 	bz_stream strm;
 
--- a/sys/src/cmd/cat.c
+++ b/sys/src/cmd/cat.c
@@ -4,7 +4,7 @@
 void
 cat(int f, char *s)
 {
-	char buf[8192];
+	char buf[IOUNIT];
 	long n;
 
 	while((n=read(f, buf, sizeof buf))>0)
--- a/sys/src/cmd/cc/cc.h
+++ b/sys/src/cmd/cc/cc.h
@@ -19,7 +19,6 @@
 typedef	struct	Bits	Bits;
 
 #define	NHUNK		50000L
-#define	BUFSIZ		8192
 #define	NSYMB		1500
 #define	NHASH		1024
 #define	STRINGSZ	200
@@ -149,7 +148,7 @@
 {
 	Io*	link;
 	char*	p;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	short	c;
 	short	f;
 };
--- a/sys/src/cmd/cc/lex.c
+++ b/sys/src/cmd/cc/lex.c
@@ -1310,7 +1310,7 @@
 		return EOF;
 	if(i->f < 0)
 		goto pop;
-	fi.c = read(i->f, i->b, BUFSIZ) - 1;
+	fi.c = read(i->f, i->b, IOUNIT) - 1;
 	if(fi.c < 0) {
 		close(i->f);
 		linehist(0, 0);
--- a/sys/src/cmd/cc/lexbody
+++ b/sys/src/cmd/cc/lexbody
@@ -558,7 +558,7 @@
 		return EOF;
 	if(i->f < 0)
 		goto pop;
-	fi.c = read(i->f, i->b, BUFSIZ) - 1;
+	fi.c = read(i->f, i->b, IOUNIT) - 1;
 	if(fi.c < 0) {
 		close(i->f);
 		linehist(0, 0);
--- a/sys/src/cmd/cfs/cfs.c
+++ b/sys/src/cmd/cfs/cfs.c
@@ -49,12 +49,11 @@
 char	statbuf[2048];
 int	statlen;
 
-#define	MAXFDATA	8192	/* i/o size for read/write */
 
-int		messagesize = MAXFDATA+IOHDRSZ;
+int		messagesize = IOUNIT+IOHDRSZ;
 
-uchar	datasnd[MAXFDATA + IOHDRSZ];
-uchar	datarcv[MAXFDATA + IOHDRSZ];
+uchar	datasnd[IOUNIT + IOHDRSZ];
+uchar	datarcv[IOUNIT + IOHDRSZ];
 
 Qid	rootqid;
 Qid	ctlqid = {0x5555555555555555LL, 0, 0};
@@ -495,7 +494,7 @@
 	long n;
 	vlong off, first;
 	char *cp;
-	char data[MAXFDATA];
+	char data[IOUNIT];
 	Ibuf *b;
 
 	off = c.thdr.offset;
@@ -607,7 +606,7 @@
 rwrite(Mfile *mf)
 {
 	Ibuf *b;
-	char buf[MAXFDATA];
+	char buf[IOUNIT];
 
 	if(statson && ctltest(mf)){
 		sendreply("read only");
--- a/sys/src/cmd/cp.c
+++ b/sys/src/cmd/cp.c
@@ -1,8 +1,6 @@
 #include <u.h>
 #include <libc.h>
 
-#define	DEFB	(8*1024)
-
 int	buflen;
 int	failed;
 int	gflag;
@@ -125,7 +123,7 @@
 
 	buflen = iounit(fdf);
 	if(buflen <= 0)
-		buflen = DEFB;
+		buflen = IOUNIT;
 
 	if(copy1(fdf, fds < 0 ? fdt : fds, from, to)==0){
 		if(fds >= 0 && write(fds, "", 0) < 0){
--- a/sys/src/cmd/crc32.c
+++ b/sys/src/cmd/crc32.c
@@ -38,7 +38,7 @@
 sum(int fd, char *name)
 {
 	int n;
-	uchar buf[8192];
+	uchar buf[IOUNIT];
 	u32int crc;
 
 	crc = init ^ xor;
--- a/sys/src/cmd/derp.c
+++ b/sys/src/cmd/derp.c
@@ -43,14 +43,10 @@
 	return v;
 }
 
-enum {
-	BUFSIZE = 8*1024,
-};
-
 int
 cmpfile(char *a, char *b)
 {
-	static uchar buf1[BUFSIZE], buf2[BUFSIZE];
+	static uchar buf1[IOUNIT], buf2[IOUNIT];
 	int r, n, m, fd1, fd2;
 	
 	if((fd1 = open(a, OREAD)) < 0)
--- a/sys/src/cmd/diff/main.c
+++ b/sys/src/cmd/diff/main.c
@@ -81,7 +81,7 @@
 {
 	int fd, i;
 	char *p;
-	char buf[8192];
+	char buf[IOUNIT];
 
 	atnotify(catch, 1);
 	p = mktemp(tmp[whichtmp++]);
--- a/sys/src/cmd/disk/9660/write.c
+++ b/sys/src/cmd/disk/9660/write.c
@@ -75,7 +75,7 @@
 writefiles(Dump *d, Cdimg *cd, Direc *direc)
 {
 	int i;
-	uchar buf[8192], digest[MD5dlen];
+	uchar buf[IOUNIT], digest[MD5dlen];
 	ulong length, n, start;
 	Biobuf *b;
 	DigestState *s;
--- a/sys/src/cmd/disk/format.c
+++ b/sys/src/cmd/disk/format.c
@@ -397,11 +397,11 @@
 {
 	long m, tot;
 
-	/* write 8k at a time, to be nice to the disk subsystem */
+	/* write IOUNIT at a time, to be nice to the disk subsystem */
 	for(tot=0; tot<n; tot+=m){
 		m = n - tot;
-		if(m > 8192)
-			m = 8192;
+		if(m > IOUNIT)
+			m = IOUNIT;
 		if(write(fd, (uchar*)buf+tot, m) != m)
 			break;
 	}
--- a/sys/src/cmd/dossrv/dosfs.h
+++ b/sys/src/cmd/dossrv/dosfs.h
@@ -1,7 +1,7 @@
 enum
 {
-	Maxfdata	= 8192,
-	Maxiosize	= IOHDRSZ+Maxfdata,
+	Maxfdata	= IOUNIT,
+	Maxiosize	= IOHDRSZ+IOUNIT,
 };
 
 extern Fcall	*req;
--- a/sys/src/cmd/exportfs/exportfs.c
+++ b/sys/src/cmd/exportfs/exportfs.c
@@ -83,7 +83,7 @@
 	if(messagesize == 0){
 		messagesize = iounit(0);
 		if(messagesize == 0)
-			messagesize = 8192+IOHDRSZ;
+			messagesize = IOUNIT+IOHDRSZ;
 	}
 	fhash = emallocz(sizeof(Fid*)*FHASHSIZE);
 
--- a/sys/src/cmd/fcp.c
+++ b/sys/src/cmd/fcp.c
@@ -1,6 +1,5 @@
 #include <u.h>
 #include <libc.h>
-#define	DEFB	(8*1024)
 #define	Nwork	8
 
 int	buflen;
@@ -134,7 +133,7 @@
 
 	buflen = iounit(fdf);
 	if(buflen <= 0)
-		buflen = DEFB;
+		buflen = IOUNIT;
 
 	if(copy1(fdf, fdt, from, to)==0 && (xflag || gflag || uflag)){
 		nulldir(&dirt);
--- a/sys/src/cmd/ip/ftpfs/ftpfs.h
+++ b/sys/src/cmd/ip/ftpfs/ftpfs.h
@@ -107,6 +107,6 @@
 #define TIMEOUT 5*60
 #define DMSYML 0x10000000
 
-#define MAXFDATA 8192
+#define MAXFDATA IOUNIT
 
 extern char	net[];		/* network for connections */
--- a/sys/src/cmd/ip/hproxy.c
+++ b/sys/src/cmd/ip/hproxy.c
@@ -1,8 +1,12 @@
 #include <u.h>
 #include <libc.h>
 
-enum { bufsize = 8*1024 };
-char buf[bufsize+1], addr[128], *proto, *host, *port, *path;
+char buf[IOUNIT+1];
+char addr[128];
+char *proto;
+char *host;
+char *port;
+char *path;
 
 void
 main(void)
@@ -13,9 +17,9 @@
 	/* read all the headers */
 	n = 0;
 	do {
-		if(n >= bufsize)
+		if(n >= IOUNIT)
 			return;
-		if((r = read(0, buf+n, bufsize-n)) <= 0)
+		if((r = read(0, buf+n, IOUNIT-n)) <= 0)
 			return;
 		n += r;
 		buf[n] = 0;
--- a/sys/src/cmd/ka/a.h
+++ b/sys/src/cmd/ka/a.h
@@ -12,7 +12,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		500
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -43,7 +42,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/kbmap.c
+++ b/sys/src/cmd/kbmap.c
@@ -137,7 +137,7 @@
 writemap(char *file)
 {
 	int i, fd, ofd;
-	char buf[8192];
+	char buf[IOUNIT];
 
 	if((fd = open(file, OREAD)) < 0){
 		fprint(2, "cannot open %s: %r", file);
--- a/sys/src/cmd/kl/l.h
+++ b/sys/src/cmd/kl/l.h
@@ -96,7 +96,6 @@
 	FPCHIP		= 1,
 	BIG		= 4096-8,
 	STRINGSZ	= 200,
-	MAXIO		= 8192,
 	MAXHIST		= 20,				/* limit of path elements for history symbols */
 	DATBLK		= 1024,
 	NHASH		= 10007,
@@ -178,8 +177,8 @@
 {
 	struct
 	{
-		uchar	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		uchar	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/kl/obj.c
+++ b/sys/src/cmd/kl/obj.c
@@ -587,7 +587,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/lens.c
+++ b/sys/src/cmd/lens.c
@@ -217,7 +217,7 @@
 	int x, y, xx, yy, dd, i;
 	int dx, dy;
 	int xoff, yoff;
-	uchar out[8192];
+	uchar out[IOUNIT];
 	uchar sp[4];
 
 	dx = (Dx(tmp->r)+mag-1)/mag;
--- a/sys/src/cmd/lnfs.c
+++ b/sys/src/cmd/lnfs.c
@@ -10,7 +10,7 @@
 {
 	OPERM	= 0x3,		/* mask of all permission types in open mode */
 	Maxsize	= 512*1024*1024,
-	Maxfdata	= 8192,
+	Maxfdata	= IOUNIT,
 	NAMELEN = 28,
 };
 
--- a/sys/src/cmd/md5sum.c
+++ b/sys/src/cmd/md5sum.c
@@ -23,7 +23,7 @@
 sum(int fd, char *name)
 {
 	int n;
-	uchar buf[8192], digest[MD5dlen];
+	uchar buf[IOUNIT], digest[MD5dlen];
 	DigestState *s;
 
 	s = md5(nil, 0, nil, nil);
--- a/sys/src/cmd/mv.c
+++ b/sys/src/cmd/mv.c
@@ -167,7 +167,7 @@
 int
 copy1(int fdf, int fdt, char *from, char *to)
 {
-	char buf[8192];
+	char buf[IOUNIT];
 	long n, n1;
 
 	while ((n = read(fdf, buf, sizeof buf)) > 0) {
--- a/sys/src/cmd/os.c
+++ b/sys/src/cmd/os.c
@@ -20,7 +20,7 @@
 
 char *mnt = "/mnt/term/cmd";
 char *dir = nil;
-char buf[8192];
+char buf[IOUNIT];
 int fd[Nfd] = {-1};
 int pid[Npid];
 int nice, foreground = 1;
--- a/sys/src/cmd/page.c
+++ b/sys/src/cmd/page.c
@@ -55,7 +55,7 @@
 
 enum {
 	NPROC = 8,
-	NBUF = 8*1024,
+	NBUF = IOUNIT,
 	NPATH = 1024,
 };
 
--- a/sys/src/cmd/paqfs/paqfs.c
+++ b/sys/src/cmd/paqfs/paqfs.c
@@ -62,7 +62,7 @@
 Fcall	rhdr, thdr;
 int 	blocksize;
 int 	cachesize = 20;
-int	mesgsize = 8*1024 + IOHDRSZ;
+int	mesgsize = IOUNIT + IOHDRSZ;
 Paq 	*root, *rootfile;
 Block 	*cache;
 ulong 	cacheage;
--- a/sys/src/cmd/pump.c
+++ b/sys/src/cmd/pump.c
@@ -37,7 +37,7 @@
 	char *file;
 
 	kilo = 5000;
-	obsize = ibsize = 8*1024;
+	obsize = ibsize = IOUNIT;
 	dsize = 0;
 	fo = 1;
 
--- a/sys/src/cmd/qa/a.h
+++ b/sys/src/cmd/qa/a.h
@@ -12,7 +12,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		8192
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -43,7 +42,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/ql/l.h
+++ b/sys/src/cmd/ql/l.h
@@ -93,7 +93,6 @@
 	FPCHIP		= 1,
 	BIG		= 32768-8,
 	STRINGSZ	= 200,
-	MAXIO		= 8192,
 	MAXHIST		= 20,				/* limit of path elements for history symbols */
 	DATBLK		= 1024,
 	NHASH		= 10007,
@@ -171,8 +170,8 @@
 {
 	struct
 	{
-		uchar	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		uchar	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/ql/obj.c
+++ b/sys/src/cmd/ql/obj.c
@@ -670,7 +670,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/qr.c
+++ b/sys/src/cmd/qr.c
@@ -699,7 +699,7 @@
 void
 main(int argc, char **argv)
 {
-	uchar buf[8192];
+	uchar buf[IOUNIT];
 	int rc;
 	int ver, lev, mode, s;
 	char *c;
--- a/sys/src/cmd/ratrace.c
+++ b/sys/src/cmd/ratrace.c
@@ -14,7 +14,7 @@
 typedef struct Msg Msg;
 struct Msg {
 	int	pid;
-	char	buf[8*1024];
+	char	buf[IOUNIT];
 };
 
 typedef struct Reader Reader;
--- a/sys/src/cmd/rc/io.c
+++ b/sys/src/cmd/rc/io.c
@@ -3,10 +3,6 @@
 #include "io.h"
 #include "fns.h"
 
-enum {
-	NBUF = 8192,
-};
-
 void
 vpfmt(io *f, char *fmt, va_list ap)
 {
@@ -247,7 +243,7 @@
 io*
 openiofd(int fd)
 {
-	return newio(emalloc(NBUF), 0, fd);
+	return newio(emalloc(IOUNIT), 0, fd);
 }
 
 /*
@@ -279,7 +275,7 @@
 				dotrap();
 		}
 		f->bufp = f->buf;
-		f->ebuf = f->buf+NBUF;
+		f->ebuf = f->buf+IOUNIT;
 	}
 }
 
@@ -294,7 +290,7 @@
 emptyiobuf(io *f)
 {
 	int n;
-	if(f->fd<0 || (n = Read(f->fd, f->buf, NBUF))<=0) return EOF;
+	if(f->fd<0 || (n = Read(f->fd, f->buf, IOUNIT))<=0) return EOF;
 	f->bufp = f->buf;
 	f->ebuf = f->buf + n;
 	return *f->bufp++;
--- a/sys/src/cmd/read.c
+++ b/sys/src/cmd/read.c
@@ -56,7 +56,7 @@
 void
 chars(int fd, char *file)
 {
-	char buf[8*1024];
+	char buf[IOUNIT];
 	vlong m;
 	int n;
 
--- a/sys/src/cmd/sha1sum.c
+++ b/sys/src/cmd/sha1sum.c
@@ -43,7 +43,7 @@
 sum(int fd, char *name)
 {
 	int n;
-	uchar buf[8192], digest[SHA2_512dlen];
+	uchar buf[IOUNIT], digest[SHA2_512dlen];
 	DigestState *s;
 
 	s = (*shafunc)(nil, 0, nil, nil);
--- a/sys/src/cmd/sum.c
+++ b/sys/src/cmd/sum.c
@@ -45,7 +45,7 @@
 	int n;
 	ulong sum;
 	uvlong fsize;
-	char buf[8*1024];
+	char buf[IOUNIT];
 
 	if(file){
 		if((fd = open(file, OREAD)) < 0){
--- a/sys/src/cmd/tee.c
+++ b/sys/src/cmd/tee.c
@@ -12,7 +12,7 @@
 int	uflag;
 int	aflag;
 
-char in[8192];
+char in[IOUNIT];
 
 int	intignore(void*, char*);
 
--- a/sys/src/cmd/touchfs.c
+++ b/sys/src/cmd/touchfs.c
@@ -5,7 +5,7 @@
 void
 Bpass(Biobuf *bin, Biobuf *bout, int n)
 {
-	char buf[8192];
+	char buf[IOUNIT];
 	int m;
 
 	while(n > 0) {
--- a/sys/src/cmd/upas/Mail/mail.h
+++ b/sys/src/cmd/upas/Mail/mail.h
@@ -6,7 +6,7 @@
 
 enum {
 	Stack	= 64*1024,
-	Bufsz	= 8192,
+	Bufsz	= IOUNIT,
 	Eventsz	= 256*UTFmax,
 	Subjlen	= 56,
 };
--- a/sys/src/cmd/upas/common/folder.c
+++ b/sys/src/cmd/upas/common/folder.c
@@ -338,10 +338,10 @@
 	char *buf;
 	int n, m;
 
-	buf = malloc(8192);
+	buf = malloc(IOUNIT);
 	for(;;){
 		m = 0;
-		n = Bread(in, buf, 8192);
+		n = Bread(in, buf, IOUNIT);
 		if(n <= 0)
 			break;
 		m = Bwrite(out, buf, n);
--- a/sys/src/cmd/va/a.h
+++ b/sys/src/cmd/va/a.h
@@ -12,7 +12,6 @@
 #define	MAXALIGN	7
 #define	FPCHIP		1
 #define	NSYMB		8192
-#define	BUFSIZ		8192
 #define	HISTSZ		20
 #define	NINCLUDE	10
 #define	NHUNK		10000
@@ -43,7 +42,7 @@
 struct	Io
 {
 	Io*	link;
-	char	b[BUFSIZ];
+	char	b[IOUNIT];
 	char*	p;
 	short	c;
 	short	f;
--- a/sys/src/cmd/vl/l.h
+++ b/sys/src/cmd/vl/l.h
@@ -163,7 +163,6 @@
 	NHUNK		= 100000,
 	MINSIZ		= 64,
 	NENT		= 100,
-	MAXIO		= 8192,
 	MAXHIST		= 20,				/* limit of path elements for history symbols */
 };
 
@@ -171,8 +170,8 @@
 {
 	struct
 	{
-		uchar	obuf[MAXIO];			/* output buffer */
-		uchar	ibuf[MAXIO];			/* input buffer */
+		uchar	obuf[IOUNIT];			/* output buffer */
+		uchar	ibuf[IOUNIT];			/* input buffer */
 	} u;
 	char	dbuf[1];
 } buf;
--- a/sys/src/cmd/vl/obj.c
+++ b/sys/src/cmd/vl/obj.c
@@ -637,7 +637,7 @@
 	n = stop - good;
 	memmove(buf, good, stop - good);
 	stop = buf + n;
-	n = MAXIO - n;
+	n = IOUNIT - n;
 	if(n > max)
 		n = max;
 	n = read(f, stop, n);
--- a/sys/src/cmd/vnc/devdraw.c
+++ b/sys/src/cmd/vnc/devdraw.c
@@ -36,7 +36,7 @@
 
 #define	NHASH		(1<<5)
 #define	HASHMASK	(NHASH-1)
-#define	IOUNIT		(64*1024)
+#define	MAXBUF		(64*1024)
 
 typedef struct Client Client;
 typedef struct Draw Draw;
@@ -1023,7 +1023,7 @@
 
 	if(c->qid.type & QTDIR){
 		c = devopen(c, omode, 0, 0, drawgen);
-		c->iounit = IOUNIT;
+		c->iounit = MAXBUF;
 	}
 
 	dlock();
@@ -1080,7 +1080,7 @@
 	c->mode = openmode(omode);
 	c->flag |= COPEN;
 	c->offset = 0;
-	c->iounit = IOUNIT;
+	c->iounit = MAXBUF;
 	return c;
 }
 
--- a/sys/src/cmd/vnc/exportfs.c
+++ b/sys/src/cmd/vnc/exportfs.c
@@ -12,8 +12,7 @@
 enum
 {
 	Nfidhash	= 32,
-	Maxfdata	= 8192,
-	Maxrpc		= IOHDRSZ + Maxfdata,
+	Maxrpc		= IOHDRSZ + IOUNIT,
 };
 
 struct Export
--- a/sys/src/cmd/wc.c
+++ b/sys/src/cmd/wc.c
@@ -8,7 +8,6 @@
  */
 #include <u.h>
 #include <libc.h>
-#define	NBUF	(8*1024)
 uvlong nline, tnline; int pline;
 uvlong nword, tnword; int pword;
 uvlong nrune, tnrune; int prune;
@@ -292,7 +291,7 @@
 count(int f, char *name)
 {
 	int n;
-	uchar buf[NBUF];
+	uchar buf[IOUNIT];
 	uchar *bufp, *ebuf;
 	uchar *state = statesp;
 
@@ -303,7 +302,7 @@
 	nchar = 0;
 
 	for(;;){
-		n=read(f, buf, NBUF);
+		n=read(f, buf, sizeof(buf));
 		if(n<=0)
 			break;
 		nchar+=n;
--- a/sys/src/cmd/webfs/http.c
+++ b/sys/src/cmd/webfs/http.c
@@ -28,7 +28,7 @@
 	int	tunnel;
 	int	len;
 	char	addr[128];
-	char	buf[8192+2];
+	char	buf[IOUNIT+UTFmax];
 };
 
 struct Hpool
@@ -549,7 +549,7 @@
 http(char *m, Url *u, Key *shdr, Buq *qbody, Buq *qpost)
 {
 	int i, l, n, try, pid, fd, cfd, needlength, chunked, retry, nobody, badauth;
-	char *s, *x, buf[8192+2], status[256], method[16], *host;
+	char *s, *x, buf[IOUNIT+UTFmax], status[256], method[16], *host;
 	vlong length, offset;
 	Url ru, tu, *nu;
 	Key *k, *rhdr;
--- a/sys/src/games/midi.c
+++ b/sys/src/games/midi.c
@@ -16,7 +16,7 @@
 int fd, ofd, div, tempo = 500000, ntrack;
 uvlong T;
 int freq[128];
-uchar out[8192], *outp = out;
+uchar out[IOUNIT], *outp = out;
 
 void *
 emallocz(int size)
--- a/sys/src/games/wadfs.c
+++ b/sys/src/games/wadfs.c
@@ -11,7 +11,7 @@
 	Nhdr = Nsig+4+4,
 	Ndict = 4+4+8,
 	Nname = 8,
-	Nbuf = 8192,
+	Nbuf = IOUNIT,
 	Maxsz = 0x7fffffff - Nhdr
 };
 
--- a/sys/src/lib9p/srv.c
+++ b/sys/src/lib9p/srv.c
@@ -830,7 +830,7 @@
 	if(srv->rpool == nil)
 		srv->rpool = allocreqpool(srv->destroyreq);
 	if(srv->msize == 0)
-		srv->msize = 8192+IOHDRSZ;
+		srv->msize = IOUNIT+IOHDRSZ;
 
 	changemsize(srv, srv->msize);
 
--- a/sys/src/libdisk/proto.c
+++ b/sys/src/libdisk/proto.c
@@ -6,11 +6,6 @@
 #include <disk.h>
 #include <regexp.h>
 
-enum {
-	LEN	= 8*1024,
-	HUNKS	= 128,
-};
-
 typedef struct File File;
 struct File{
 	char	*new;
--- a/sys/src/libdraw/openfont.c
+++ b/sys/src/libdraw/openfont.c
@@ -5,18 +5,17 @@
 static char*
 readfile(char *name)
 {
-	enum { HUNK = 8*1024, };
 	int f, n, r;
 	char *s, *p;
 
 	n = 0;
 	r = -1;
-	if((s = malloc(HUNK)) != nil){
+	if((s = malloc(IOUNIT)) != nil){
 		if((f = open(name, OREAD|OCEXEC)) >= 0){
-			while((r = read(f, s+n, HUNK)) > 0){
+			while((r = read(f, s+n, IOUNIT)) > 0){
 				n += r;
 				r = -1;
-				if((p = realloc(s, n+HUNK)) == nil)
+				if((p = realloc(s, n+IOUNIT)) == nil)
 					break;
 				s = p;
 			}
--- a/sys/src/libdraw/readimage.c
+++ b/sys/src/libdraw/readimage.c
@@ -30,7 +30,7 @@
 	if(d != nil)
 		chunk = d->bufsize - 32;	/* a little room for header */
 	else
-		chunk = 8192;
+		chunk = IOUNIT;
 
 	/*
 	 * distinguish new channel descriptor from old ldepth.
--- a/sys/src/libflate/deflate.c
+++ b/sys/src/libflate/deflate.c
@@ -50,7 +50,7 @@
 	 * internal lz paramaters
 	 */
 	DeflateOut	= 4096,			/* output buffer size */
-	BlockSize	= 8192,			/* attempted input read quanta */
+	BlockSize	= IOUNIT,		/* attempted input read quanta */
 	DeflateBlock	= DeflateMaxBlock & ~(BlockSize - 1),
 	MinMatchMaxOff	= 4096,			/* max profitable offset for small match;
 						 * assumes 8 bits for len, 5+10 for offset