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Reduce bss usage and speed up string printing

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text	   data	    bss	    dec	    hex	filename
 237913	    660	  49284	 287857	  46471	strace.before
 237973	    660	  28772	 267405	  4148d	strace

This reduces L1 D-cache pressure a bit: instead of dirtying
20k of bss, we will reuse already dirty stack area.

* util.c (printpathn): Use on-stack buffers instead of static ones.
Saves 5*MAXPATHLEN in bss.
(printstr): Use tprints() instead of tprintf("%s") when printing
formatted string. May be a bit faster, depending on libc.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko 2012-01-19 17:20:23 +01:00
parent 7d55801ae9
commit b3c52cf02a
1 changed files with 17 additions and 18 deletions
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35
util.c
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@ -427,8 +427,6 @@ printuid(const char *text, unsigned long uid)
tprintf((uid == -1) ? "%s%ld" : "%s%lu", text, uid);
}
static char path[MAXPATHLEN + 1];
/*
* Quote string `instr' of length `size'
* Write up to (3 + `size' * 4) bytes to `outstr' buffer.
@ -566,6 +564,8 @@ string_quote(const char *instr, char *outstr, int len, int size)
void
printpathn(struct tcb *tcp, long addr, int n)
{
char path[MAXPATHLEN + 1];
if (!addr) {
tprints("NULL");
return;
@ -581,24 +581,25 @@ printpathn(struct tcb *tcp, long addr, int n)
if (umovestr(tcp, addr, n + 1, path) < 0)
tprintf("%#lx", addr);
else {
static char outstr[4*(sizeof path - 1) + sizeof "\"...\""];
const char *fmt;
char *outstr;
int trunc = (path[n] != '\0');
if (trunc)
path[n] = '\0';
string_quote(path, outstr, -1, n + 1);
fmt = "%s";
n++;
outstr = alloca(4 * n); /* 4*(n-1) + 2 for quotes */
string_quote(path, outstr, -1, n);
tprints(outstr);
if (trunc)
fmt = "%s...";
tprintf(fmt, outstr);
tprints("...");
}
}
void
printpath(struct tcb *tcp, long addr)
{
printpathn(tcp, addr, sizeof path - 1);
/* Size must correspond to char path[] size in printpathn */
printpathn(tcp, addr, MAXPATHLEN);
}
/*
@ -612,7 +613,7 @@ printstr(struct tcb *tcp, long addr, int len)
static char *str = NULL;
static char *outstr;
int size;
const char *fmt;
int ellipsis;
if (!addr) {
tprints("NULL");
@ -623,9 +624,7 @@ printstr(struct tcb *tcp, long addr, int len)
str = malloc(max_strlen + 1);
if (!str)
die_out_of_memory();
}
if (!outstr) {
outstr = malloc(4 * max_strlen + sizeof "\"...\"");
outstr = malloc(4 * max_strlen + /*for quotes:*/ 2);
if (!outstr)
die_out_of_memory();
}
@ -651,12 +650,12 @@ printstr(struct tcb *tcp, long addr, int len)
}
}
fmt = "%s";
if (string_quote(str, outstr, len, size) &&
(len < 0 || len > max_strlen))
fmt = "%s...";
ellipsis = (string_quote(str, outstr, len, size) &&
(len < 0 || len > max_strlen));
tprintf(fmt, outstr);
tprints(outstr);
if (ellipsis)
tprints("...");
}
#if HAVE_SYS_UIO_H