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Mold the redbean binary to minimize page faults

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This change brings page faults for precompressed static asset serving
down from 27 to 20 (or fewer) after fork. This is more of an art than
science. Hopefully Blinkenlights can visualize page faults soon.
This commit is contained in:
Justine Tunney 2021-05-03 12:09:35 -07:00
parent 2d34819779
commit e56a9d0e23
14 changed files with 978 additions and 782 deletions
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43
libc/runtime/ftrace.c
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@ -23,9 +23,13 @@
#include "libc/calls/internal.h"
#include "libc/calls/struct/sigset.h"
#include "libc/dce.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/repmovsb.h"
#include "libc/macros.internal.h"
#include "libc/nexgen32e/rdtsc.h"
#include "libc/nexgen32e/rdtscp.h"
#include "libc/nexgen32e/stackframe.h"
#include "libc/nexgen32e/x86feature.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/nt/thunk/msabi.h"
@ -49,6 +53,7 @@
void ftrace_hook(void);
static int noreentry;
static uint64_t laststamp;
static char g_buf[512];
static const char *g_lastsymbol;
static struct SymbolTable *g_symbols;
@ -70,11 +75,14 @@ static noasan int GetNestingLevel(struct StackFrame *frame) {
* according to the System Five NexGen32e ABI.
*/
privileged noasan void ftrace(void) {
size_t i, j, nesting;
char *p;
uint64_t stamp;
const char *symbol;
struct StackFrame *frame;
size_t nesting, symbolsize;
if (!cmpxchg(&noreentry, 0, 1)) return;
if (g_symbols) {
stamp = rdtsc();
frame = __builtin_frame_address(0);
frame = frame->next;
symbol =
@ -84,31 +92,30 @@ privileged noasan void ftrace(void) {
g_symbols->count,
frame->addr - g_symbols->addr_base)]
.name_rva];
if (symbol != g_lastsymbol &&
(nesting = GetNestingLevel(frame)) * 2 < ARRAYLEN(g_buf) - 4) {
i = 2;
j = 0;
while (nesting--) {
asm volatile("" : : : "memory");
g_buf[i++] = ' ';
g_buf[i++] = ' ';
if (symbol != g_lastsymbol) {
symbolsize = strlen(symbol);
nesting = GetNestingLevel(frame);
if (2 + nesting * 2 + symbolsize + 1 + 21 + 2 <= ARRAYLEN(g_buf)) {
p = g_buf;
*p++ = '+';
*p++ = ' ';
memset(p, ' ', nesting * 2);
p += nesting * 2;
p = mempcpy(p, symbol, symbolsize);
*p++ = ' ';
p += uint64toarray_radix10((stamp - laststamp) / 3.3, p);
*p++ = '\r';
*p++ = '\n';
write(2, g_buf, p - g_buf);
}
while (i < ARRAYLEN(g_buf) - 2 && symbol[j]) {
asm volatile("" : : : "memory");
g_buf[i++] = symbol[j++];
}
g_buf[i++] = '\r';
g_buf[i++] = '\n';
write(2, g_buf, i);
}
g_lastsymbol = symbol;
laststamp = X86_HAVE(RDTSCP) ? rdtscp(0) : rdtsc();
}
noreentry = 0;
}
textstartup void ftrace_install(void) {
g_buf[0] = '+';
g_buf[1] = ' ';
if ((g_symbols = OpenSymbolTable(FindDebugBinary()))) {
__hook(ftrace_hook, g_symbols);
} else {